A wavelength selective switch, test apparatus, design method and spatial light modulator

Abstract

The application relates to a wavelength selective switch, a test device, a design method and a spatial light modulator. The wavelength selective switch comprises a spatial light modulator, the spatial light modulator is loaded with a non-uniform period grating, the non-uniform period grating comprises a plurality of repeating period units, each of the repeating period units comprises a period of S first pixels and a period of T second pixels, wherein S and T are positive integers. According to the application, the non-uniform period grating is loaded on the spatial light modulator, each of the repeating period units of the non-uniform period grating comprises a period of S first pixels and a period of T second pixels, the proportion of S and T is changed to realize the design of different non-uniform period gratings, and through the design of the non-uniform period grating, the equivalent period of the grating is not limited to an integer number of pixels in the traditional sense, so that the light can be deflected more effectively and with high resolution; and the pixel size does not need to be changed, and a higher-resolution LCOS also does not need to be used.

Description

Technical Field

[0001] This application relates to the field of wavelength selective switching device technology, specifically to a wavelength selective switch, testing equipment, design method, and spatial light modulator. Background Technology

[0002] As data center interconnects, metropolitan area networks, and long-haul optical networks evolve towards 400 G / 800 G and even 1 T, traditional fixed-grid ROADMs are no longer sufficient to meet the multiple demands for bandwidth, latency, and energy consumption. Elastic Optical Networks (EON) have become the recognized direction of evolution. Wavelength selective switches (WSS), as the core device of ROADMs, are upgrading their function from "static filtering" to "programmable optical crossover." The accuracy and speed of beam deflection directly determine the wavelength-port reconstruction granularity, network congestion probability, and energy consumption.

[0003] Among related technologies, liquid crystal on silicon (LCOS) offers a novel light deflection mechanism for liquid crystal slabs (WSS) due to its advantages such as no mechanical movement, programmable pixels, and low driving voltage. However, when facing the light deflection problem in practical applications, current spatial light modulators (LCOS) achieve beam deflection by changing the uniform period of the entire pixel. Limited by the physical size of the pixel, they cannot overcome the "single pixel" barrier. Using higher resolution LCOS would lead to problems such as increased chip area, increased driving complexity, and higher costs.

[0004] Therefore, it is necessary to design a new wavelength selective switch to overcome the above problems. Summary of the Invention

[0005] This application provides a wavelength selective switch, a testing device, a design method, and a spatial light modulator, which can solve the technical problems in related technologies that are limited by the physical size of pixels and the increase in chip area, resulting in increased complexity and cost.

[0006] In a first aspect, embodiments of this application provide a wavelength selection switch, comprising: a spatial light modulator, wherein a non-uniform periodic grating is loaded on the spatial light modulator, the non-uniform periodic grating comprising a plurality of repetitive periodic units, each of the repetitive periodic units comprising S periods of first pixels and T periods of second pixels, wherein S and T are both positive integers.

[0007] In conjunction with the first aspect, in one embodiment, the first pixel is N pixels, and the second pixel is N... i Pixel, N i =N±1.

[0008] In conjunction with the first aspect, in one embodiment, in each of the repeating periodic units, the periods of the S first pixels are arranged sequentially, and the periods of the T second pixels are arranged sequentially after the period of the last first pixel.

[0009] In conjunction with the first aspect, in one embodiment, in each of the repeating periodic units, the period of the first pixel and the period of the second pixel are alternately arranged.

[0010] In conjunction with the first aspect, in one embodiment, in each of the repeating periodic units, a portion of the periods of the first pixels are arranged before the periods of the T second pixels, and another portion of the periods of the first pixels are arranged after the periods of the T second pixels.

[0011] Secondly, embodiments of this application provide a testing device, which includes: an adjustable wavelength light source and a wavelength selection switch connected to the adjustable wavelength light source, wherein the wavelength selection switch is the wavelength selection switch described above.

[0012] In conjunction with the second aspect, in one embodiment, the testing equipment further includes an optical power meter connected to the wavelength selection switch.

[0013] Thirdly, embodiments of this application provide a design method for the aforementioned wavelength selective switch, which includes the following steps: Find the optimal uniform period for the wavelength corresponding to the target port of the wavelength selection switch; Adjust the proportion of this optimal uniform period within the repeating period unit and obtain the spectral diagrams corresponding to different proportions; Find the non-uniform periodic grating with the highest power in the spectrum and use it as the corresponding wavelength loading grating.

[0014] In conjunction with the third aspect, in one embodiment, adjusting the proportion of the optimal uniform period within the repetition period unit includes: gradually decreasing the proportion of the optimal uniform period within the repetition period unit from 100%.

[0015] Fourthly, embodiments of this application provide a spatial light modulator, on which a non-uniform periodic grating is loaded. The non-uniform periodic grating includes a plurality of repeating periodic units, each of which includes S periods of first pixels and T periods of second pixels, wherein S and T are both positive integers.

[0016] The beneficial effects of the technical solutions provided in this application include: By loading a non-uniform periodic grating onto a spatial light modulator, each repetitive periodic unit in the non-uniform periodic grating includes S periods of the first pixel and T periods of the second pixel. Changing the ratio of S to T can achieve the design of different non-uniform periodic gratings. Moreover, through this non-uniform periodic grating design, the equivalent period of the grating is not limited to an integer number of pixels in the traditional sense, thus enabling more effective high-resolution deflection of light. Furthermore, it does not require changing the pixel size or using a higher resolution LCOS, meaning it is not limited by the physical size of the pixel and does not suffer from the problems of increased chip area, increased driving complexity, and increased cost caused by higher resolution LCOS. This solves the technical problems of being limited by the physical size of the pixel and the increased complexity and cost of the chip area in related technologies. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of one large period of a uniform periodic grating in related technologies; Figure 2 A schematic diagram of one large period of a non-uniform periodic grating provided in an embodiment of this application; Figure 3 This is a connection diagram of a testing device provided in an embodiment of this application; Figure 4 A power comparison diagram of uniform period and non-uniform period gratings provided in the embodiments of this application. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0020] This application provides a wavelength selective switch, a testing device, a design method, and a spatial light modulator, which can solve the technical problems in related technologies that are limited by the physical size of pixels and the increase in chip area, resulting in increased complexity and cost.

[0021] In a first aspect, embodiments of this application provide a wavelength selection switch, which may include: a spatial light modulator, wherein a non-uniform periodic grating is loaded on the spatial light modulator, the non-uniform periodic grating includes a plurality of repetitive periodic units, each of the repetitive periodic units including S periods of first pixels and T periods of second pixels, wherein S and T are both positive integers.

[0022] In this embodiment, a non-uniform periodic grating is loaded onto the spatial light modulator (LCOS). This non-uniform periodic grating uses a period of S first pixels plus a period of T second pixels as a large period (see [link]). Figure 2 As shown), this large periodic sequence is repeated, unlike the uniform periodic gratings in related technologies which repeat with the same fixed number of pixels at a periodicity. Figure 1 (As shown). This embodiment can achieve the design of different non-uniform periodic gratings by changing the ratio of S to T. It should be understood that the number of pixels in the first pixel and the second pixel in this embodiment are different.

[0023] This embodiment loads a non-uniform periodic grating onto a spatial light modulator. Each repetitive periodic unit in the non-uniform periodic grating includes a period of S first pixels and a period of T second pixels. By changing the ratio of S to T, different non-uniform periodic grating designs can be achieved. Furthermore, through this non-uniform periodic grating design, the equivalent period of the grating is not limited to an integer number of pixels in the traditional sense, thus enabling more effective high-resolution deflection of light. Moreover, it does not require changing the pixel size or using a higher resolution LCOS, meaning it is not limited by the physical size of the pixels and avoids the problems of increased chip area, increased driving complexity, and increased cost associated with higher resolution LCOS. This solves the technical problems of being limited by the physical size of pixels and the increased complexity and cost of the chip area in related technologies.

[0024] In the above embodiments, the high-resolution deflection principle of the non-uniform periodic grating is as follows: based on the small-angle deflection formula: .

[0025] In the formula, This is the deflection angle; The pixel size; The number of pixels in one large period; The wavelength of light is denoted by λ. Through this non-uniform periodic grating design, the effective number of pixels of the grating (that is, the number of pixels in one large period) is not limited to an integer number of pixels in the traditional sense, thus enabling more efficient high-resolution deflection of light.

[0026] For example, see Figure 1As shown, in a traditional uniform periodic grating, if a large period consists entirely of N pixels, then the equivalent number of pixels in a large period is N. See also... Figure 2 As shown, in the non-uniform periodic grating of this embodiment, there are four N-pixel periods and two N-pixel periods within one large period. i If we consider the period of a pixel, then the equivalent number of pixels in one large period is four N pixels and two N pixels. i The average number of pixels, not N pixels. This average can be an integer or a decimal, allowing you to obtain any desired number of pixels.

[0027] Furthermore, in one embodiment, the first pixel is N pixels, and the second pixel is N... i Pixel, N i =N±1. In this embodiment, for example, if N is 18, then N i Choose 17 or 19, selecting the integer closest to N. This results in better uniformity across a large period of the grating and less impact on the grating's power. See also Figure 2 As shown, assuming a large period contains four 18-pixel periods and two 19-pixel periods, the equivalent pixel count of this large period is the average of the four 18-pixel and two 19-pixel periods, which is 18.33. By adjusting the allocation ratio and values ​​of the first and second pixels, any equivalent pixel count can be obtained. For example, if we need to obtain a large period with an equivalent pixel count of 18.5, we can set three 18-pixel periods and three 19-pixel periods, thus accurately obtaining 18.5 pixels and achieving high-resolution beam deflection. Figure 1 The uniform grating shown can only produce an integer number of equivalent pixels, not a fractional number like 18.5, thus preventing precise deflection.

[0028] Further, in one embodiment, in each of the repeating periodic units, the periods of the S first pixels are arranged sequentially, and the periods of the T second pixels are arranged sequentially after the period of the last first pixel. This embodiment illustrates one arrangement of the periods of the S first pixels and the periods of the T second pixels, that is, it can be like... Figure 2 As shown, periods with the same number of pixels are arranged together sequentially, while periods with different numbers of pixels are arranged one after the other. Figure 2 In the middle, when N is 18, N i When the value is 19, four 18-pixel periods are arranged sequentially, and then two 19-pixel periods are arranged after the four 18-pixel periods.

[0029] Furthermore, in some optional embodiments, in each of the repeating periodic units, the period of the first pixel and the period of the second pixel are arranged alternately. This embodiment illustrates another arrangement of S periods of the first pixel and T periods of the second pixel, that is, the periods of the first pixel and the periods of the second pixel are arranged alternately. For example, one period of the first pixel is followed by one period of the second pixel, and then one period of the first pixel is arranged after the period of the second pixel, and so on. For example, it could also be two periods of the first pixel, followed by two periods of the second pixel, and then two periods of the first pixel are arranged after the two periods of the second pixel, and so on. Alternatively, one period of the first pixel can be arranged in the middle, and then one period of the second pixel can be arranged on both sides of the period of the first pixel, and then one period of the first pixel can be arranged after each period of the second pixel, and so on. Of course, other arrangements are also possible, as long as the periods of the first pixel and the periods of the second pixel are alternately arranged. With such an arrangement, a more uniform pixel period can be obtained, with less impact on the power of the grating. For example, if a large cycle contains four 18-pixel cycles and two 19-pixel cycles, you can arrange two 18-pixel cycles, then one 19-pixel cycle, then two more 18-pixel cycles, and finally one 19-pixel cycle.

[0030] Further, in one embodiment, in each of the repeating periodic units, a portion of the periods of the first pixels are arranged before the T periods of the second pixels, and another portion of the periods of the first pixels are arranged after the T periods of the second pixels. This embodiment illustrates another arrangement of the S periods of the first pixels and the T periods of the second pixels, that is, in a large period, all the periods of the second pixels are arranged in the middle of the large period, and a portion of the periods of the first pixels are arranged before all the periods of the second pixels, and another portion of the periods of the first pixels are arranged after all the periods of the second pixels. For example, in a large period with 4 periods of 18 pixels and 2 periods of 19 pixels, the 2 periods of 19 pixels can be arranged in the middle, the 2 periods of 18 pixels can be arranged before the 2 periods of 19 pixels, and the other 2 periods of 18 pixels can be arranged after the 2 periods of 19 pixels.

[0031] The non-uniform periodic grating designed in this application embodiment is used in the LCOS section of a wavelength selective switch (WSS) to make the angle of light deflection from the incident port to the target output port of the WSS more precise, thereby improving the optical power of the target port of the WSS.

[0032] Secondly, embodiments of this application provide a testing device, which may include: an adjustable wavelength light source and a wavelength selection switch connected to the adjustable wavelength light source, wherein the wavelength selection switch is the wavelength selection switch described above.

[0033] This embodiment establishes a testing device, including at least a tunable wavelength light source and a wavelength selection switch. The tunable wavelength light source can be a laser, capable of providing light sources of different wavelengths. The wavelength selection switch deflects the input light to a designated output port, and then a power meter can be used to measure the optical power at the output port. See also... Figure 3 As shown, the wavelength selection switch has four output ports: output port 1, output port 2, output port 3, and output port 4.

[0034] Preferably, the aforementioned testing equipment further includes an optical power meter, which is connected to the wavelength selection switch. See also Figure 3 As shown, one embodiment is illustrated in which the optical power meter is connected to the output port 4 of the wavelength selection switch.

[0035] The aforementioned testing equipment can be used to test wavelength selective switches and design a grating that corresponds to the optimal uniform period of the wavelength at the target port of the wavelength selective switch.

[0036] Thirdly, embodiments of this application provide a design method for the aforementioned wavelength selective switch, which may include the following steps: S1: Find the optimal uniform period for the wavelength corresponding to the target port of the wavelength selection switch.

[0037] S2: Adjust the proportion of the optimal uniform period within the repeating period unit and obtain the spectrum corresponding to different proportions.

[0038] S3: Find the non-uniform periodic grating with the highest power in the spectrum as the corresponding wavelength loading grating.

[0039] In this embodiment, for example, the optimal uniform period of the wavelength corresponding to the target port of the wavelength selection switch is 18. Within a large period, the proportion of the period of 18 pixels is adjusted and a spectrum is obtained. The spectrum shows the optical power corresponding to different proportions. Then, the proportion of the period of 18 pixels corresponding to the highest power in the spectrum is found, and a non-uniform period grating is designed based on this proportion as the corresponding wavelength loading grating.

[0040] Furthermore, in one embodiment, adjusting the proportion of the optimal uniform period within the repetition period unit includes: gradually decreasing the proportion of the optimal uniform period within the repetition period unit from 100%.

[0041] In this embodiment, the specific design steps are as follows: 1. Find the optimal uniform period corresponding to the wavelength of the target port of the wavelength selection switch. 2. Obtain non-uniform period gratings with different proportions by successively decreasing the proportion of the optimal uniform period within the large period from 100% to 10%. 3. Observe the spectrum and find the non-uniform period grating corresponding to the highest power as the corresponding wavelength loading grating.

[0042] In other embodiments, the proportion of the optimal uniform period within the large period can be gradually decreased from 80%, or other non-decreasing methods can be used to adjust the proportion of the optimal uniform period within the large period. No limitations are imposed here.

[0043] See Figure 4 The figure shows a power comparison graph of uniform and non-uniform periodic gratings. In this graph, the horizontal axis represents wavelength, and the vertical axis represents insertion loss. In the graph, 18 represents a period of 18 pixels, 19 represents a period of 19 pixels, and the percentages represent the proportion of each pixel's period within a large period. For example, 18=30%, 19=70%, meaning that within a large period, the 18-pixel period accounts for 30%, and the 19-pixel period accounts for 70%. The last one, "full of 19," indicates that all periods are 19 pixels, and this grating is a uniform periodic grating. From this graph, it is clear that the non-uniform periodic grating, regardless of its percentage, obtains higher optical power than the uniform periodic grating.

[0044] Fourthly, embodiments of this application also provide a spatial light modulator, wherein a non-uniform periodic grating is loaded on the spatial light modulator, the non-uniform periodic grating includes a plurality of repeating periodic units, each of the repeating periodic units including S periods of first pixels and T periods of second pixels, wherein S and T are both positive integers.

[0045] In this embodiment, a non-uniform periodic grating is loaded onto the spatial light modulator (LCOS). This non-uniform periodic grating uses a period of S first pixels plus a period of T second pixels as a large period (see [link]). Figure 2 As shown), this large periodic sequence is repeated, unlike the uniform periodic gratings in related technologies which repeat with the same fixed number of pixels at a periodicity. Figure 1 (As shown). This embodiment can achieve the design of different non-uniform periodic gratings by changing the ratio of S to T. It should be understood that the number of pixels in the first pixel and the second pixel in this embodiment are different.

[0046] This embodiment loads a non-uniform periodic grating onto a spatial light modulator. Each repetitive periodic unit in the non-uniform periodic grating includes a period of S first pixels and a period of T second pixels. By changing the ratio of S to T, different non-uniform periodic grating designs can be achieved. Furthermore, through this non-uniform periodic grating design, the equivalent period of the grating is not limited to an integer number of pixels in the traditional sense, thus enabling more effective high-resolution deflection of light. Moreover, it does not require changing the pixel size or using a higher resolution LCOS, meaning it is not limited by the physical size of the pixels and avoids the problems of increased chip area, increased driving complexity, and increased cost associated with higher resolution LCOS. This solves the technical problems of being limited by the physical size of pixels and the increased complexity and cost of the chip area in related technologies.

[0047] With this non-uniform periodic grating design, the equivalent number of pixels of the grating (that is, the number of pixels in one large period) is not limited to an integer number of pixels in the traditional sense, thus enabling more efficient high-resolution deflection of light.

[0048] For example, see Figure 1 As shown, in a traditional uniform periodic grating, if a large period consists entirely of N pixels, then the equivalent number of pixels in a large period is N. See also... Figure 2 As shown, in the non-uniform periodic grating of this embodiment, there are four N-pixel periods and two N-pixel periods within one large period. i If we consider the period of a pixel, then the equivalent number of pixels in one large period is four N pixels and two N pixels. i The average number of pixels, not N pixels. This average can be an integer or a decimal, allowing you to obtain any desired number of pixels.

[0049] Furthermore, in one embodiment, the first pixel is N pixels, and the second pixel is N... i Pixel, N i =N±1. In this embodiment, for example, if N is 18, then N i Choose 17 or 19, selecting the integer closest to N. This results in better uniformity across a large period of the grating and less impact on the grating's power. See also Figure 2 As shown, assuming a large period contains four 18-pixel periods and two 19-pixel periods, the equivalent pixel count of this large period is the average of the four 18-pixel and two 19-pixel periods, which is 18.33. By adjusting the allocation ratio and values ​​of the first and second pixels, any equivalent pixel count can be obtained. For example, if we need to obtain a large period with an equivalent pixel count of 18.5, we can set three 18-pixel periods and three 19-pixel periods, thus accurately obtaining 18.5 pixels and achieving high-resolution beam deflection. Figure 1 The uniform grating shown can only produce an integer number of equivalent pixels, not a fractional number like 18.5, thus preventing precise deflection.

[0050] Further, in one embodiment, in each of the repeating periodic units, the periods of the S first pixels are arranged sequentially, and the periods of the T second pixels are arranged sequentially after the period of the last first pixel. This embodiment illustrates one arrangement of the periods of the S first pixels and the periods of the T second pixels, that is, it can be like... Figure 2 As shown, periods with the same number of pixels are arranged together sequentially, while periods with different numbers of pixels are arranged one after the other. Figure 2 In the middle, when N is 18, N i When the value is 19, four 18-pixel periods are arranged sequentially, and then two 19-pixel periods are arranged after the four 18-pixel periods.

[0051] Furthermore, in some optional embodiments, in each of the repeating periodic units, the period of the first pixel and the period of the second pixel are arranged alternately. This embodiment illustrates another arrangement of S periods of the first pixel and T periods of the second pixel, that is, the periods of the first pixel and the periods of the second pixel are arranged alternately. For example, one period of the first pixel is followed by one period of the second pixel, and then one period of the first pixel is arranged after the period of the second pixel, and so on. For example, it could also be two periods of the first pixel, followed by two periods of the second pixel, and then two periods of the first pixel are arranged after the two periods of the second pixel, and so on. Alternatively, one period of the first pixel can be arranged in the middle, and then one period of the second pixel can be arranged on both sides of the period of the first pixel, and then one period of the first pixel can be arranged after each period of the second pixel, and so on. Of course, other arrangements are also possible, as long as the periods of the first pixel and the periods of the second pixel are alternately arranged. With such an arrangement, a more uniform pixel period can be obtained, with less impact on the power of the grating. For example, if a large cycle contains four 18-pixel cycles and two 19-pixel cycles, you can arrange two 18-pixel cycles, then one 19-pixel cycle, then two more 18-pixel cycles, and finally one 19-pixel cycle.

[0052] Further, in one embodiment, in each of the repeating periodic units, a portion of the periods of the first pixels are arranged before the T periods of the second pixels, and another portion of the periods of the first pixels are arranged after the T periods of the second pixels. This embodiment illustrates another arrangement of the S periods of the first pixels and the T periods of the second pixels, that is, in a large period, all the periods of the second pixels are arranged in the middle of the large period, and a portion of the periods of the first pixels are arranged before all the periods of the second pixels, and another portion of the periods of the first pixels are arranged after all the periods of the second pixels. For example, in a large period with 4 periods of 18 pixels and 2 periods of 19 pixels, the 2 periods of 19 pixels can be arranged in the middle, the 2 periods of 18 pixels can be arranged before the 2 periods of 19 pixels, and the other 2 periods of 18 pixels can be arranged after the 2 periods of 19 pixels.

[0053] The non-uniform periodic grating designed in this application embodiment is used in the LCOS part of WSS, so that the angle of light deflection from the incident port to the target output port of WSS is more accurate, thereby improving the optical power of the target port of WSS.

[0054] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0055] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0056] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A wavelength selective switch, characterized in that, It includes: A spatial light modulator, wherein a non-uniform periodic grating is loaded on the spatial light modulator, the non-uniform periodic grating comprising a plurality of repeating periodic units, each repeating periodic unit comprising S periods of first pixels and T periods of second pixels, wherein S and T are both positive integers.

2. The wavelength selective switch as described in claim 1, characterized in that, The first pixel is N pixels, and the second pixel is N. i Pixel, N i =N±1.

3. The wavelength selective switch as described in claim 1, characterized in that, In each of the repetitive periodic units, the S periods of the first pixels are arranged sequentially, and the T periods of the second pixels are arranged sequentially after the period of the last first pixel.

4. The wavelength selective switch as described in claim 1, characterized in that, In each of the repetitive periodic units, the period of the first pixel and the period of the second pixel are alternately arranged.

5. The wavelength selective switch as described in claim 1, characterized in that, In each of the repetitive periodic units, a portion of the periods of the first pixel are arranged before the T periods of the second pixel, and another portion of the periods of the first pixel are arranged after the T periods of the second pixel.

6. A testing device, characterized in that, It includes: An adjustable wavelength light source and a wavelength selection switch connected to the adjustable wavelength light source, wherein the wavelength selection switch is the wavelength selection switch as described in claim 1.

7. The testing equipment as described in claim 6, characterized in that, The testing equipment also includes an optical power meter, which is connected to the wavelength selection switch.

8. A design method for a wavelength selective switch as described in claim 1, characterized in that, It includes the following steps: Find the optimal uniform period for the wavelength corresponding to the target port of the wavelength selection switch; Adjust the proportion of this optimal uniform period within the repeating period unit and obtain the spectral diagrams corresponding to different proportions; Find the non-uniform periodic grating with the highest power in the spectrum and use it as the corresponding wavelength loading grating.

9. The design method as described in claim 8, characterized in that, The adjustment of the proportion of the optimal uniform period within the repetition period unit includes: The percentage of the optimal uniform period within the repeating period unit is decreased sequentially from 100%.

10. A spatial light modulator, characterized in that, The spatial light modulator is loaded with a non-uniform periodic grating, which includes multiple repetitive periodic units. Each repetitive periodic unit includes S periods of first pixels and T periods of second pixels, where S and T are both positive integers.

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