Wavelength selective switch

Abstract

The application provides a wavelength selective switch. The wavelength selective switch comprises, in sequence along the light transmission direction: an input end; a light beam shaping element, which is used for shaping the composite light of the input end; a metasurface grating, which is located on the light output side of the light beam shaping element and is used for diffracting and splitting the composite light passing through the light beam shaping element to form a plurality of single-wavelength lights; a channel switching reflection element, which is used for receiving and reflecting the plurality of single-wavelength lights; and output ends, which are used for receiving the plurality of single-wavelength lights reflected by the channel switching reflection element, and are in one-to-one correspondence with the plurality of single-wavelength lights. The application solves the problems of complex optical path and low transmission efficiency of the wavelength selective switch in the prior art.

Description

Technical Field

[0001] This invention relates to the field of optical communication equipment technology, and more specifically, to a wavelength selection switch. Background Technology

[0002] As the communications industry places increasing emphasis on high-speed data transmission and massive information processing, there is a growing need for new products with higher performance and reliability. Simultaneously, all-optical networks are expanding from the backbone and metropolitan area core to the metropolitan area aggregation and access layers to provide end-to-end reachability and flexibility for optical signals. Wavelength Selective Switches (WSS), as a crucial component of Reconfigurable Optical Add-Drop Multiplexers (ROADMs), face demands for more channels and greater bandwidth, while also requiring miniaturization and lower costs.

[0003] Currently, there are three mainstream technologies for realizing wavelength selective switching: microelectromechanical systems (MEMS), liquid crystal (LC) technology, and liquid crystal on silicon (LCOS) technology. The diffraction and beam splitting elements used in these three technologies are traditional etched gratings. Etching gratings have high insertion loss and poor light transmission efficiency. Furthermore, these etched gratings are polarization-sensitive elements, only capable of diffracting and splitting ordinary light (o-rays) parallel to the grating direction. Therefore, before the beam enters the grating, a polarizing beam splitter prism or birefringent crystal YVO4 is needed to separate the ordinary light (o-rays) and extraordinary light (e-rays). A polarization conversion element, such as a half-wave plate, is also required to convert the o-rays into e-rays. Thus, the two output beams have the same polarization direction, both being p-rays relative to the grating. During the beam return process, after passing through the etched grating, a portion of the e-beam needs to be converted into o-beams, and the o-beams and e-beams are then combined to compress the beam spot and maintain a balanced ratio of o-beams to e-beams. This increases the material cost of these polarization conversion components and complicates the engineering assembly.

[0004] In other words, wavelength selective switches in existing technologies suffer from complex optical paths and low transmission efficiency. Summary of the Invention

[0005] The main objective of this invention is to provide a wavelength selective switch to solve the problems of complex optical paths and low transmission efficiency in existing wavelength selective switches.

[0006] To achieve the above objectives, the present invention provides a wavelength selective switch, comprising: an input terminal; a beam shaping element for shaping the composite light at the input terminal; a metasurface grating located on the light-emitting side of the beam shaping element for diffracting and splitting the composite light passing through the beam shaping element to form multiple single-wavelength lights; a channel switching reflector for receiving and reflecting the multiple single-wavelength lights; and an output terminal for receiving the multiple single-wavelength lights reflected by the channel switching reflector. There are multiple output terminals, each corresponding to one of the multiple single-wavelength lights.

[0007] Furthermore, the wavelength selection switch also includes an optical path analysis element, which is located between the metasurface grating and the channel switching reflective element. The optical path analysis element is used to analyze and shape the incident light.

[0008] Furthermore, at least one surface of the optical path analysis element has a metasurface structure.

[0009] Furthermore, the optical path analysis element includes multiple analysis units arranged in an array, with different analysis units used to analyze and shape light of different wavelengths.

[0010] Furthermore, each analytical unit has an independent metasurface structure, and the metasurface structures of different analytical units are different.

[0011] Furthermore, the input end and multiple output ends are located on the side of the beam shaping device away from the metasurface grating. The light of multiple wavelengths reflected by the channel switching reflection element passes sequentially through the optical path analysis element, the metasurface grating and the beam shaping element before entering the multiple output ends.

[0012] Furthermore, the wavelength selection switch also includes a reflector, which may be one or more, with at least one reflector disposed between the optical path analysis element and the channel switching reflector to deflect the optical path between the optical path analysis element and the channel switching reflector.

[0013] Furthermore, the metasurface grating is either a transmissive metasurface grating or a reflective metasurface grating.

[0014] Furthermore, a metasurface grating includes multiple microstructures within one cycle, with different types of microstructures having different shapes, while microstructures of the same type have the same shape and size.

[0015] Furthermore, the channel switching reflective element is a micromirror array, which includes multiple microlenses, each of which has a reflective surface. Different microlenses are used to reflect light of different wavelengths, and the reflection angle of each microlens can be adjusted.

[0016] Furthermore, the input terminal is an input collimator, and / or the output terminal is an output collimator.

[0017] Furthermore, the beam shaping element includes one of a beam expander and a prism.

[0018] According to the technical solution of this invention, the wavelength selection switch includes an input terminal, a beam shaping element, a metasurface grating, a channel switching reflector, and an output terminal arranged sequentially along the light transmission direction. The beam shaping element is used to shape the composite light at the input terminal; the metasurface grating is located on the light-emitting side of the beam shaping element and is used to diffract and split the composite light passing through the beam shaping element to form multiple single-wavelength lights; the channel switching reflector is used to receive and reflect the multiple single-wavelength lights; the output terminal is used to receive the multiple single-wavelength lights reflected by the channel switching reflector, and there are multiple output terminals, each corresponding to one of the multiple single-wavelength lights.

[0019] By using metasurface gratings, their polarization insensitivity avoids the need for numerous polarization conversion components in wavelength selective switches, saving components, reducing costs, simplifying assembly, improving efficiency, and reducing energy loss. Furthermore, the high transmission efficiency of metasurface gratings ensures minimal loss of light transmission efficiency during diffraction, maintaining a polarization-free response, and achieving dispersion comparable to traditional diffraction gratings, thus fulfilling the diffraction separation function required in wavelength selective switches. Moreover, the high precision of metasurface gratings, fabricated using semiconductor processing technology, allows for flexible adjustment of the grating period to suit different wavelengths, enabling free control of the separation interval and increasing design flexibility. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 A schematic diagram of the incident optical path of a wavelength selective switch according to an optional embodiment of the present invention is shown;

[0022] Figure 2 It shows Figure 1 A schematic diagram of the output optical path of the wavelength selection switch in the image;

[0023] Figure 3 It shows Figure 1 A schematic diagram of the structure of the metasurface grating in the image;

[0024] Figure 4 It shows Figure 1A schematic diagram of the optical path analysis element in the diagram;

[0025] Figure 5 It shows Figure 1 A schematic diagram of the optical path of the micromirror array.

[0026] The above figures include the following reference numerals:

[0027] 10. Input terminal; 20. Beam shaping element; 30. Metasurface grating; 31. Microstructure; 40. Optical path analysis element; 41. Analysis unit; 50. Micromirror array; 60. Output terminal; 70. Mirror. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0030] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0031] To address the problems of complex optical paths and low transmission efficiency in existing wavelength selective switches, this invention provides a wavelength selective switch.

[0032] like Figures 1 to 5 As shown, the wavelength selection switch includes an input terminal 10, a beam shaping element 20, a metasurface grating 30, a channel switching reflector, and an output terminal 60 arranged sequentially along the light transmission direction. The beam shaping element 20 is used to shape the composite light from the input terminal 10. The metasurface grating 30 is located on the light-emitting side of the beam shaping element 20 and is used to diffract and split the composite light passing through the beam shaping element 20 to form multiple single-wavelength lights. The channel switching reflector is used to receive and reflect multiple single-wavelength lights. The output terminal 60 is used to receive multiple single-wavelength lights reflected by the channel switching reflector. There are multiple output terminals 60, and each output terminal 60 corresponds to a single-wavelength light.

[0033] By incorporating a metasurface grating 30, its polarization insensitivity avoids the need for numerous polarization conversion components in the wavelength selective switch, saving components, reducing costs, simplifying assembly, improving efficiency, and reducing energy loss. Furthermore, the high transmission efficiency of the metasurface grating 30 ensures minimal loss of light transmission efficiency and polarization-free response during diffraction, achieving dispersion comparable to traditional diffraction gratings, thus fulfilling the diffraction separation function required in the wavelength selective switch. Moreover, the metasurface grating 30 is fabricated using semiconductor processing technology, ensuring high precision. Its period can be flexibly adjusted for different wavelengths, allowing for free control of the separation interval and increasing design flexibility.

[0034] It should be noted that the above-mentioned metasurface grating 30 includes a flat substrate and a metasurface nanostructure 31 disposed on one or both surfaces of the flat substrate.

[0035] like Figure 1 and Figure 2 As shown, the wavelength selection switch also includes an optical path analysis element 40, located between the metasurface grating 30 and the channel switching reflective element. The optical path analysis element 40 is used to analyze and shape the incident light. The wavelength selection switch also includes a reflector 70, which can be one or more. At least one reflector 70 is disposed between the optical path analysis element 40 and the channel switching reflective element to deflect the optical path between them. In actual optical path construction, the number and specific position of the reflectors 70 can be set according to the actual situation, and are not limited to the number and position shown in the figures of this application. By setting the reflectors 70, the optical path can be deflected, changing the overall layout of the optical path, and the optical path can be deflected according to different spaces.

[0036] Specifically, the channel switching reflective element is a micromirror array 50, which includes multiple microlenses, each with a corresponding reflective surface. Different microlenses are used to reflect light of different wavelengths, and the reflection angle of each microlens can be adjusted. The adjustable reflection angle of each microlens means that the deflection angle of each microlens is determined by its driving voltage.

[0037] like Figure 1As shown, in the incident light path, the composite light emitted from the input end 10 is expanded by the beam shaping element 20 and hits the metasurface grating 30 at a diffraction angle. After the diffraction and beam splitting by the metasurface grating 30, the composite light is divided into multiple single-wavelength lights. The light of different wavelengths propagates separately at different diffraction angles and is incident on the optical path analysis element 40. The optical path analysis element 40 analyzes and shapes the light of different wavelengths to achieve beam convergence. Then, the light path is deflected by the reflector 70, and finally, the light spots of different wavelengths hit the reflective surface of the corresponding individual microlenses in the micromirror array 50.

[0038] like Figure 2 As shown, in the outgoing optical path, the light rays incident on the reflective surface of the microlens of the specific microlens array 50 are reflected at different angles when the microlenses are deflected at different angles under different voltages. The reflected light rays are deflected by the optical path of the reflector 70, analyzed and shaped by the optical path analysis element 40, and then hit the metasurface grating 30 in reverse. After being reverse-converged by the beam shaping element 20, they are received by the corresponding output terminal 60.

[0039] Specifically, due to the different deflection angles of the microlenses in the micromirror array 50, the distance from the output end 60 to the input end 10 varies. Combined with the dimensions of the output end 60 itself, multiple output ends 60 can be arranged in an array. Therefore, the deflection angle of the microlenses directly determines which output end 60 the output optical path will reach. The deflection angle of the microlenses is determined by their driving voltage, thus controlling the switching of wavelength channels is achieved through the driving voltage.

[0040] Specifically, in the incident light path, the beam shaping element 20 aims to shape the light spot, generally by expanding it to match the size and area of ​​the metasurface grating 30. During beam expansion, it is not necessarily required that the expansion be proportional to the horizontal and vertical directions; for example, a circular spot can be expanded into a circular spot, or into an elliptical spot. The beam shaping element 20 in this application uses either a beam expanding lens or a prism to achieve beam expansion, but other beam expanding elements are also possible.

[0041] exist Figure 1 and Figure 2In the specific embodiment shown, the metasurface grating 30 is a reflective metasurface grating. In this case, in the above-mentioned incident light path, the reflective metasurface grating is used to diffract and split the incident composite light, and then output multiple single-wavelength lights in the form of reflection. Similarly, in the above-mentioned outgoing light path, the light that hits the reflective metasurface grating in the opposite direction is also reflected to the beam shaping element 20. The input end 10 and the multiple output ends 60 are all located on the side of the beam shaping device away from the metasurface grating 30. The multiple wavelengths of light reflected by the micromirror array 50 pass through the optical path analysis element 40, the metasurface grating 30 and the beam shaping element 20 in sequence and then enter the multiple output ends 60 accordingly. That is to say, in the outgoing light path, the optical path analysis element 40, the metasurface grating 30 and the beam shaping element 20 all act on the optical path. Figure 2 It can be equivalent to Figure 1 The side view, in Figure 1 In the middle, the position of the output end 60 is the same as that of the input end 10, which is located on the side of the beam shaping element 20 away from the reflective metasurface grating.

[0042] In another embodiment not shown in the figure, the metasurface grating 30 is a transmissive metasurface grating. In this case, in the above-mentioned incident light path, the transmissive metasurface grating is used to diffract and split the incident composite light and then output multiple single-wavelength lights in a transmitted form; similarly, in the above-mentioned outgoing light path, the light that hits the transmissive metasurface grating in the opposite direction is also transmitted to the beam shaping element 20.

[0043] It should be noted that this application only uses the metasurface grating 30 as a reflective metasurface grating as an example, but in actual applications, the type of metasurface grating 30 can be selected according to the actual situation.

[0044] like Figure 3 As shown, the left figure illustrates a schematic diagram of the metasurface grating 30 of this application, and the right figure illustrates a schematic diagram of the microstructure 31 within a single period in the left figure. The metasurface grating 30, designed based on the principle of diffraction, can achieve the same dispersion as a traditional diffraction grating while maintaining essentially no loss in light transmission efficiency and polarization-free response through a rationally designed nanostructure 31, thus realizing the diffraction beam splitting function required in wavelength selective switches. Since the metasurface grating 30 uses semiconductor technology to realize the nanoscale microstructure 31 of the metasurface, it has high precision and allows for flexible adjustment of the grating period. The grating period can be adjusted according to different requirements for diffraction angles at different wavelengths, achieving free control of the beam splitting interval. Furthermore, due to different metasurface design methods, the projection shape of the microstructure 31 of the metasurface grating 30 onto the substrate of the metasurface grating 30 can be cylindrical, L-shaped, triangular, or other shapes, or combinations of various shapes.

[0045] Specifically, one cycle of the metasurface grating 30 includes multiple microstructures 31, each with several of each type. Different types of microstructures 31 have different shapes, while microstructures of the same type have the same shape and size. For example... Figure 3 As shown, the metasurface grating 30 includes three types of microstructures 31 within one cycle. These three microstructures 31 are circular, L-shaped, and triangular, respectively. Microstructures of the same type are arranged at intervals along a first direction, while microstructures of different types are arranged at intervals along a second direction, with the first and second directions perpendicular to each other. Of course, microstructures 31 of different shapes can be incorporated into one cycle of the metasurface grating 30 according to actual conditions, and the number of types of microstructures 31 can be increased or decreased, not limited to those shown in the figure.

[0046] Specifically, after the light beam is diffracted and split by the metasurface grating 30, it needs to be analyzed and shaped before reaching the micromirror array 50. The goal is to match the size of the light spot corresponding to the wavelength with the area of ​​the reflecting surface of the corresponding wavelength on the micromirror array 50. This results in better isolation between channels and channel wavelength bandwidth. At least one side of the optical path analysis element 40 has a metasurface structure. Since the optical path analysis element 40 is used to appropriately converge the light of various wavelengths output from the metasurface grating 30 and correspond one-to-one with the positions of multiple microlenses in the micromirror array 50, designing the optical path analysis element 40 with a metasurface helps to increase the transmission efficiency of the optical path analysis element 40, avoid the loss of light energy, and ensure the accuracy of the incident light on the micromirror array 50.

[0047] like Figure 4As shown, the optical path analysis element 40 includes multiple analysis units 41 arranged in an array. This can also be understood as dividing one side surface of the optical path analysis element 40 into a grid to form multiple small grid regions, each of which is an analysis unit 41. Different analysis units 41 are used to analyze and shape light of different wavelengths. Each analysis unit 41 has an independent metasurface structure, and the metasurface structures of different analysis units 41 are different. The optical path analysis element 40 is divided into multiple analysis units 41, and each analysis unit 41 has a corresponding metasurface structure. The metasurface structures of the multiple analysis units 41 are all different. Due to the semiconductor processing technology of the metasurface structure, the metasurface design is combined with the optical path analysis element 40, so that the multiple analysis units 41 can analyze and shape light of different wavelengths. The multiple analysis units 41 can be arranged and designed according to the spacing of multiple single-wavelength light and their corresponding shaping and analysis requirements. This setting ensures that each single-wavelength light has a corresponding analysis unit 41 to achieve one-to-one optimal analysis and modulation, thereby matching the size of the single-wavelength light spot with the size of the corresponding microlens in the micromirror array 50. The multiple analysis units 41 can be closely connected to achieve full coverage of the area, thereby avoiding losses caused by light field leakage.

[0048] It should be noted that in the incident light path, the multiple single-wavelength lights output by the metasurface grating 30 correspond one-to-one with the multiple analysis units 41 of the optical path analysis element 40. Similarly, in the outgoing light path, the multiple wavelengths of light reflected by the micromirror array 50 also correspond one-to-one with the multiple analysis units 41 of the optical path analysis element 40. Due to the diffraction and dispersion by the metasurface grating 30 and the angular deflection of the reflected light by the micromirror array 50, the geometric position of each wavelength of light in the optical path analysis element 40 is fixed and identical when passing through the optical path analysis element 40 in either the forward or reverse direction. Since the optical path analysis element 40 can be designed with metasurfaces and fabricated using semiconductor processes, it is possible to design independent metasurface structures for individual wavelengths, arrange metasurface structures of different wavelengths in an array, and fabricate them in one step to form a whole.

[0049] against Figure 4 It should also be noted that the metasurface structures of each analysis unit 41 in the figure are for illustrative purposes only and are not the actual shapes of the metasurface structures. They are only used to illustrate that the metasurface structures of different analysis units 41 are different.

[0050] In a specific embodiment of this application, input terminal 10 is an input collimator, and output terminal 60 is an output collimator. Figure 1 and Figure 2In the illustrated embodiment, there is one input collimator and four output collimators. However, this application does not limit the number of output collimators, and different numbers of output collimators can be set according to requirements.

[0051] Furthermore, this application employs metasurface design for the metasurface grating 30 and the optical path analysis element 40. Since the metasurface grating 30 and the optical path analysis element 40 can be periodically and freely arranged according to the wavelength of light, the beam propagation direction can be adjusted, and the spot shape can be shaped, the spot size and spacing of each wavelength on the micromirror array 50 can be controlled, thus reducing the requirements for the design and fabrication of the micromirror array 50.

[0052] Furthermore, conventionally ground lenses cannot adjust the local curvature of the lens, nor can they independently control the wavelength of light passing through different positions of the lens. Even array lenses that can be designed with freeform surfaces face industrialization bottlenecks such as expensive molds, size limitations, and high requirements for materials and equipment. Therefore, the metasurface optical path analysis element 40, which can achieve array-based control and be fabricated in a single low-cost process, has a wide range of applications beyond wavelength selective switching.

[0053] Specifically, the micromirror array 50 of this application is a micromirror array of MEMS. The micromirror array 50 also includes a drive control unit for driving the deflection angle of the microlenses. Multiple microlenses are fabricated on a silicon chip using single conductor wafer processing technology. The drive control unit drives the microlenses to deflect, thereby controlling the direction of the reflected light from the microlenses.

[0054] like Figure 5 The diagram shows the deflection of a single microlens in the micromirror array 50. The microlenses can have different deflection angles, so that the reflected light can have different exit angles.

[0055] Obviously, the embodiments described above are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0056] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0057] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wavelength selective switch, characterized in that, Including those arranged sequentially along the direction of light transmission: Input terminal (10); A beam shaping element (20) is used to shape the composite light at the input end (10); Metasurface grating (30) is located on the light-emitting side of the beam shaping element (20). The metasurface grating (30) is used to diffract and split the composite light that has passed through the beam shaping element (20) to form multiple single-wavelength lights. A channel-switching reflective element, wherein the channel-switching reflective element is used to receive and reflect the plurality of single-wavelength light; Output terminal (60), the output terminal (60) is used to receive the plurality of single-wavelength light reflected by the channel switching reflective element, the output terminal (60) is multiple, and the multiple output terminals (60) correspond one-to-one with the plurality of single-wavelength light; The wavelength selection switch also includes an optical path analysis element (40), which is located between the metasurface grating (30) and the channel switching reflection element. The optical path analysis element (40) is used to analyze and shape the incident light.

2. The wavelength selective switch according to claim 1, characterized in that, At least one side of the optical path analysis element (40) has a metasurface structure.

3. The wavelength selective switch according to claim 1, characterized in that, The optical path analysis element (40) includes multiple analysis units (41), which are arranged in an array. Different analysis units (41) are used to analyze and shape light of different wavelengths.

4. The wavelength selective switch according to claim 3, characterized in that, Each of the analysis units (41) has an independent metasurface structure, and the metasurface structures of different analysis units (41) are different.

5. The wavelength selective switch according to claim 1, characterized in that, The input terminal (10) and the multiple output terminals (60) are located on the side of the beam shaping device away from the metasurface grating (30). The light of multiple wavelengths reflected by the channel switching reflection element passes through the optical path analysis element (40), the metasurface grating (30) and the beam shaping element (20) in sequence and then enters the multiple output terminals (60).

6. The wavelength selective switch according to claim 1, characterized in that, The wavelength selection switch further includes a reflector (70), which may be one or more, with at least one reflector (70) disposed between the optical path analysis element (40) and the channel switching reflector to deflect the optical path between the optical path analysis element (40) and the channel switching reflector.

7. The wavelength selective switch according to claim 1, characterized in that, The metasurface grating (30) is a transmissive metasurface grating or a reflective metasurface grating.

8. The wavelength selective switch according to claim 1, characterized in that, The metasurface grating (30) includes a variety of microstructures (31) within one cycle. Each type of microstructure (31) includes multiple microstructures. The shapes of the microstructures (31) of different types are different, while the shapes and sizes of the microstructures (31) of the same type are the same.

9. The wavelength selective switch according to claim 1, characterized in that, The channel switching reflective element is a micromirror array (50), which includes multiple microlenses, each of which has a reflective surface. Different microlenses are used to reflect light of different wavelengths, and the reflection angle of each microlens can be adjusted.

10. The wavelength selective switch according to any one of claims 1 to 9, characterized in that, The input terminal (10) is an input collimator, and / or the output terminal (60) is an output collimator.

11. The wavelength selective switch according to any one of claims 1 to 9, characterized in that, The beam shaping element (20) includes one of a beam expander and a prism.

Images