Optical modulator, wavelength selective switch, port-level optical switch, optical cross connection and optical communication system

Abstract

Provided in the embodiments of the present application are an optical modulator, a wavelength selective switch, a port-level optical switch, an optical cross connection and an optical communication system, which aim to reduce the insertion loss during optical switching. In the optical modulator provided in the present application, an included angle is formed between a first surface of a first substrate and a second surface of a second substrate, and a liquid crystal layer is located between the first substrate and the second substrate, such that an included angle is formed between an incident light beam of a signal light beam irradiating the optical modulator and an emergent light beam emitted from the optical modulator. In addition, the first substrate is provided with a first electrode layer, the second substrate is provided with a second electrode layer, the first electrode layer and the second electrode layer are adjusted such that electric fields of different intensities are generated to change the refractive index of the liquid crystal layer, and the included angle between the incident light beam and the emergent light beam is further adjusted, thereby directing the signal light beam toward a target output port. Moreover, the signal light beam is deflected on the basis of the principle of refraction, thereby reducing the insertion loss of the signal light beam in the optical modulator, and further reducing the insertion loss during optical switching.

Description

Optical modulators, wavelength selective switches, port-level optical switches, optical cross-connects, and optical communication systems

[0001] This application claims priority to Chinese patent application filed on October 31, 2024, with application number 202411551540.9 and entitled "Optical modulator, wavelength selective switch, port-level optical switch, optical cross-connect and optical communication system", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical switching technology, specifically to an optical modulator, a wavelength selective switch, a port-level optical switch, an optical cross-connect, and an optical communication system. Background Technology

[0003] An optical fiber array has one input port and multiple output ports. The light beam is directed from the input port to the optical modulator, which deflects the beam to a designated output port to achieve optical switching. The optical modulator includes a liquid crystal layer, and the voltage of the liquid crystal in different regions of the liquid crystal layer is independently controlled to cause different rotations of the liquid crystal in different regions, forming a blazed grating. The beam is deflected by light diffraction. However, due to the loss of light during the diffraction process, there is a large insertion loss during the optical switching process. Summary of the Invention

[0004] This application provides an optical modulator, a wavelength selective switch, a port-level optical switch, an optical cross-connect, and an optical communication system, aiming to reduce insertion loss during optical switching.

[0005] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0006] On one hand, this application provides an optical modulator, which includes a first substrate, a second substrate, and a liquid crystal layer. The first substrate has a first electrode layer and is capable of transmitting light beams. The second substrate is spaced apart from the first substrate in the thickness direction of the optical modulator. The second substrate has a second electrode layer and is capable of reflecting light beams toward the first substrate or transmitting light beams, and is located between the first substrate and the second substrate. The first electrode layer and the second electrode layer are used to generate an electric field that drives the liquid crystal in the liquid crystal layer to deflect. The first substrate includes a first surface facing the second substrate, and the second substrate includes a second surface facing the first substrate. The distance between the first surface and the second surface gradually increases along a preset direction, and the thickness of the liquid crystal layer also gradually increases along a preset direction. The preset direction is parallel to the second surface and perpendicular to the thickness direction of the optical modulator.

[0007] In the optical modulator provided in this application, the first substrate is capable of transmitting a light beam, and the second substrate is capable of reflecting the light beam toward the first substrate or transmitting the light beam. An angle exists between the first surface of the first substrate and the second surface of the second substrate. A liquid crystal layer is located between the first and second substrates, creating an angle between the incident light beam illuminating the optical modulator and the outgoing light beam emitted from the optical modulator. Furthermore, a first electrode layer is provided on the first substrate, and a second electrode layer is provided on the second substrate. By adjusting the electric fields of different intensities generated by the first and second electrode layers, the refractive index of the liquid crystal layer is changed, further adjusting the angle between the incident and outgoing light beams, causing the signal beam to be directed toward the target output port. The deflection of the signal beam is achieved through the principle of refraction, reducing insertion loss of the signal beam in the optical modulator, thereby reducing insertion loss during the optical switching process.

[0008] In some embodiments, the light modulator further includes a frame located between the first substrate and the second substrate, and disposed around the liquid crystal layer; the frame includes a first portion and a second portion opposite to each other in a predetermined direction, the thickness of the first portion being less than the thickness of the second portion. An angle is formed between the plane containing the first surface and the plane containing the second surface.

[0009] In some embodiments, the included angle between the first surface and the second surface is less than or equal to 30°.

[0010] The above settings prevent excessive thickness differences in the liquid crystal layer between the first and second substrates, which could lead to uneven modulation of the signal beam by the liquid crystal layer and prevent the deflected signal beam from reaching the target output port.

[0011] In some embodiments, the liquid crystal in the liquid crystal layer is a dual-frequency liquid crystal. A first electrode layer and a second electrode layer provide the dual-frequency liquid crystal with either a first electric field frequency or a second electric field frequency, where the first electric field frequency is lower than the second electric field frequency. At the first electric field frequency, the long axis of the liquid crystal molecules in the dual-frequency liquid crystal extends along a first direction; at the second electric field frequency, the long axis of the liquid crystal molecules extends along a second direction, and the first and second directions intersect. By adjusting the electric field frequency, the process of the liquid crystal molecules rotating to a specified angle or returning to their initial angle in the dual-frequency liquid crystal can be accelerated, thereby improving the efficiency of the optical modulator in achieving optical switching.

[0012] In some embodiments, the first electrode layer is configured to transmit a common voltage; the second electrode layer includes a plurality of second electrodes, which are extended along a preset direction and are spaced apart along a direction perpendicular to the preset direction.

[0013] With the above configuration, the arrangement of multiple second electrodes is aligned with the direction in which the signal beam is split, allowing signal beams of different wavelengths to irradiate different regions of the liquid crystal layer. By adjusting the voltage of the multiple second electrodes, different regions of the liquid crystal layer can be made to have different refractive indices, thereby deflecting the signal beams of different wavelengths at different angles and directing them towards their respective target output ports. Simultaneously, for each individual second electrode, its extension direction is perpendicular to the direction in which the signal beam is split, ensuring that a signal beam of a certain wavelength remains within the same region of the liquid crystal layer during deflection. The refractive index of this region of the liquid crystal layer remains constant, reducing insertion loss during the deflection process.

[0014] In some embodiments, the second substrate is further provided with multiple driving circuits, each driving circuit being electrically connected to a second electrode, and the driving circuit being used to provide a driving voltage to the second electrode. Through this configuration, by individually controlling the voltage of each second electrode using the driving circuit, the refractive index of the liquid crystal in the corresponding region of each second electrode can be adjusted individually, thereby enabling the deflection of light beams illuminating different regions at different angles, improving the flexibility of the optical modulator.

[0015] In some embodiments, the first electrode layer includes a plurality of first electrodes, which extend along a preset direction and are spaced apart along a direction perpendicular to the preset direction; the second electrode layer is configured to transmit a common voltage.

[0016] With the above configuration, the arrangement direction of the multiple first electrodes is the same as the direction in which the signal beam is split, allowing signal beams of different wavelengths to irradiate different regions of the liquid crystal layer. By adjusting the voltage of the multiple first electrodes, different regions of the liquid crystal layer can have different refractive indices, thereby achieving different angles of deflection for signal beams of different wavelengths, and thus directing signal beams of different wavelengths towards their respective target output ports. Simultaneously, for each individual first electrode, the extension direction of the first electrode is perpendicular to the direction in which the signal beam is split, ensuring that a signal beam of a certain wavelength remains within the same region of the liquid crystal layer during deflection, maintaining a constant refractive index and reducing insertion loss during deflection. Furthermore, compared to the previous embodiment where the first electrode layer was configured with a common voltage, this embodiment configures the second electrode layer with a common voltage and sets multiple first electrodes on the first electrode layer, further reducing insertion loss in the optical modulator by facilitating the projection of the signal beam from the first substrate into the liquid crystal layer.

[0017] In some embodiments, the optical modulator further includes a polarization conversion film layer located between the second substrate and the liquid crystal layer. The polarization conversion film layer converts light with other polarization directions into light with a specific polarization direction, thereby improving the utilization efficiency of the light beam.

[0018] In some embodiments, the optical modulator further includes an alignment layer located between the first substrate and the liquid crystal layer, and / or, an alignment layer located between the liquid crystal layer and the second substrate. The alignment layer may define the initial alignment direction and angle of the liquid crystal in the liquid crystal layer.

[0019] On the other hand, this application embodiment also provides a wavelength selective switch, which includes an optical fiber array, a grating, a lens, and the aforementioned optical modulator, wherein the second substrate is capable of reflecting a light beam toward the first substrate; the grating, the lens, and the optical modulator are arranged sequentially, and the optical fiber array includes an input port and multiple output ports, which are spaced apart along a preset direction.

[0020] In some embodiments, the wavelength selection switch further includes a polarization processing device, and the polarization processing device, grating, lens, and optical modulator are arranged sequentially. The polarization processing device can modulate the signal beam into polarized light, reducing the influence of the liquid crystal on the polarized light, thereby reducing the insertion loss of the signal beam in the optical modulator. Through the above arrangement, the polarization processing device can filter light with a specific polarization direction, or convert light with other polarization directions into light with a specific polarization direction, thereby improving the utilization efficiency of the light beam.

[0021] In some embodiments, the wavelength selective switch further includes an optical prism, which has a first outer wall, a second outer wall, and a third outer wall. The first and third outer walls are disposed opposite each other and are adjacent to the second outer wall. An optical fiber array and an optical modulator are disposed on the first outer wall, with the optical modulator located on the side of the optical fiber array closer to the second outer wall. A grating is disposed on the second outer wall. A reflector is formed on the third outer wall. The light beam input to the optical fiber array passes through the reflector to the grating, and then through the reflector to the optical modulator. This configuration improves the integration of the wavelength selective switch, fully utilizes the space between the grating, lens, and optical modulator, and reduces the size of the wavelength selective switch.

[0022] This application embodiment also provides another port-level optical switch, which includes an input port, an output port, multiple polarization control units, multiple birefringent units, and the aforementioned optical modulator. The second substrate is capable of transmitting light beams. The polarization control units and birefringent units are located between the input port and the optical modulator. The multiple polarization control units and multiple birefringent units are alternately arranged along the propagation direction of the light beam input through the input port. The input port and the output port are located on both sides of the optical modulator.

[0023] In another aspect, embodiments of this application also provide an optical cross-connection, which includes multiple ports and the aforementioned wavelength selection switch, the wavelength selection switch being used to achieve cross-interconnection between the multiple ports.

[0024] In another aspect, embodiments of this application also provide another type of optical cross-connection, which includes multiple ports and the aforementioned port-level optical switch. The port-level optical switch is used to realize cross-interconnection between multiple ports.

[0025] In another aspect, embodiments of this application also provide an optical communication system, which includes the aforementioned optical cross-connect and optical add-drop multiplexing devices, and the optical cross-connect and optical add-drop multiplexing devices are connected.

[0026] In another aspect, embodiments of this application also provide an optical filter, which includes the aforementioned optical modulator, optical fiber array, and detector, wherein the optical fiber array and the optical modulator are arranged sequentially, and the detector is connected to the optical modulator.

[0027] In another aspect, embodiments of this application also provide an optical amplifier, which includes the optical filter described above.

[0028] In another aspect, embodiments of this application also provide an optical communication system, which includes the optical amplifier described above.

[0029] It is understood that the beneficial effects of the wavelength selection switch, optical cross-connect, optical filter, optical amplifier and optical communication system provided in the above embodiments of this application can be referred to the beneficial effects of the optical modulator mentioned above, and will not be repeated here. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in some embodiments of this application will be briefly described below. Obviously, the drawings described below are only drawings of some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of this application.

[0031] Figure 1 is a schematic diagram of the wavelength selection switch in an embodiment of this application;

[0032] Figure 2 is a schematic diagram of the optical modulator in an embodiment of this application;

[0033] Figure 3 is a schematic diagram of the optical modulator in an embodiment of this application.

[0034] Figure 4 is a schematic diagram of the structure of the first substrate and the second substrate in an embodiment of this application;

[0035] Figure 5 is a schematic diagram of the structure of the first substrate and the second substrate in the embodiments of this application;

[0036] Figure 6 is a schematic diagram of the structure of the optical modulator in the embodiment of this application;

[0037] Figure 7 is a schematic diagram of the wavelength selection switch in an embodiment of this application.

[0038] Figure 8 is a schematic diagram of the wavelength selection switch in an embodiment of this application.

[0039] Figure 9 is a schematic diagram of the optical modulator in an embodiment of this application;

[0040] Figure 10 is a schematic diagram of the wavelength selection switch in an embodiment of this application;

[0041] Figure 11 is a schematic diagram of the wavelength selection switch in an embodiment of this application;

[0042] Figure 12 is a schematic diagram of the wavelength selection switch in an embodiment of this application.

[0043] Figure 13 is a schematic diagram of the port-level optical switch in an embodiment of this application;

[0044] Figure 14 is a schematic diagram of the optical filter structure in an embodiment of this application;

[0045] Figure 15 is a schematic diagram of the optical filter structure in an embodiment of this application.

[0046] Explanation of reference numerals in the attached figures: 200, wavelength selection switch; 210, fiber array; 220, grating; 230, lens group; 100, optical modulator; 211, input port; 212, output port; 10, first substrate; 20, second substrate; 30, liquid crystal layer; 40, reflective film; 11, first electrode layer; 21, second electrode layer; 50, frame; 51, first part; 52, second part; 110, first electrode; 210, second electrode ; 31, Liquid crystal molecule; 60, Polarization processing device; 61, Polarization control unit; 62, Birefringence unit; 231, First lens; 232, Second lens; 70, Polarization conversion film layer; 80, Optical prism; 81, First outer wall; 82, Second outer wall; 83, Third outer wall; 90, Orientation layer; 300, Optical filter; 301, Detector; 302, Beam splitter; 303, Adjustable mirror; 304, Lens; 400, Port-level optical switch. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0048] Hereinafter, 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. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature.

[0049] Furthermore, in the embodiments of this application, directional terms such as "up," "down," "left," "right," "horizontal," and "vertical" 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.

[0050] In the embodiments of this application, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium.

[0051] It should be noted that, in the description of the embodiments of this application, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection or an integral connection; they can also refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0052] On one hand, embodiments of this application provide an optical communication system, which can be an optical communication network composed of a reconfigurable optical add / drop multiplexer (ROADM) and an optical cross-connect (OXC), enabling automated control in an all-optical network. The OXC is an optical transmission device capable of exchanging optical signals between different optical paths.

[0053] Referring to Figure 1, the optical cross-connect also includes a wavelength selective switch (WSS) 200. The wavelength selective switch 200 is used to select and adjust the wavelength of the optical signal to realize multi-wavelength transmission and wavelength division multiplexing technology in the optical fiber communication system. When an optical signal enters the wavelength selective switch 200, the wavelength selective switch 200 can select an optical signal of a specific wavelength and output it.

[0054] The wavelength selective switch 200 includes an optical fiber array 210, a grating 220, a lens group 230 (which may include multiple lenses), and an optical modulator 100. The optical fiber array 210 consists of an input port 211 and multiple output ports 212. During the cross-interconnection between the input port 211 and the output ports 212 in the wavelength selective switch 200, one of the multiple output ports 212 in the optical fiber array 210 can be configured as the target output port. An optical signal is input from the input port 211, passes through the grating 220, the lens group 230, and the optical modulator 100, and is directed to the target output port, thereby completing the optical switching. The optical signal is transmitted in the form of a signal beam, and the grating 220, the lens group 230, and the optical modulator 100 are arranged sequentially. The grating 220 can be positioned before the lens group 230, with the signal beam passing through the grating 220 before passing through the lens group 230; alternatively, the grating 220 can be positioned after the lens group 230, with the signal beam passing through the lens group 230 before passing through the grating 220; or the grating 220 can be positioned between multiple lenses in the lens group 230, with the signal beam passing through several lenses, then through the grating 220, and then through the remaining lenses. For example, in the embodiment where the grating 220 is positioned before the lens group 230, the signal beam is diffracted by the grating 220, causing different wavelengths of the signal beam to disperse into different angles. The dispersed signal beam is then collimated by the lens group 230, illuminating the optical modulator 100. The optical modulator 100 then deflects the signal beams of different wavelengths as required, and the beams are combined and restored again by the grating 220 and the lens group 230, directing the deflected signal beams towards the target output port.

[0055] Referring to Figures 1, 2, and 3, the optical modulator 100 provided in this application includes a first substrate 10 and a second substrate 20. The first substrate 10 is capable of transmitting a light beam (i.e., a signal beam). The second substrate 20 is spaced apart from the first substrate 10 in the thickness direction of the optical modulator 100. The second substrate 20 can either reflect the light beam toward the first substrate 10 or transmit the light beam. The optical modulator 100 also includes a liquid crystal layer 30 located between the first substrate 10 and the second substrate 20. The liquid crystal layer 30 is formed of liquid crystal. The signal beam, which is split by the grating 220 and collimated by the lens group 230, is incident on the optical modulator 100 from one side of the first substrate 10. The first substrate 10 may include a conductive glass plate, such as ITO (Indium Tin Oxide) conductive glass, through which the signal beam can pass to the liquid crystal layer 30.

[0056] Referring to Figures 2 and 3, in embodiments where the second substrate 20 can reflect a light beam toward the first substrate 10, the second substrate 20 may include a CMOS circuit backplane or a thin-film transistor (TFT). A reflective film 40 is provided on the side of the second substrate 20 facing the first substrate 10. Exemplarily, the reflective film 40 may include at least one of a metal reflective film and an electrolyte reflective film. In embodiments where the second substrate 20 can transmit a light beam, the second substrate 20 may include a thin-film transistor (TFT) glass panel.

[0057] In an optical modulator 100 based on the second substrate 20 that can reflect a light beam toward the first substrate 10, the input port 211 and output port 212 of the fiber array 210 in the wavelength selection switch 200 are both located on the same side of the optical modulator 100; in an optical modulator 100 based on the second substrate 20 that can transmit a light beam, the input port 211 and output port 212 of the fiber array 210 in the wavelength selection switch 200 are respectively located on both sides of the optical modulator 100.

[0058] In the above embodiments, the first substrate 10 includes a first surface facing the second substrate 20, and the second substrate 20 includes a second surface facing the first substrate 10. The distance between the first surface and the second surface gradually increases along a preset direction (i.e., there is an angle between the plane containing the first surface and the plane containing the second surface). The preset direction is parallel to the second surface and perpendicular to the thickness direction of the light modulator 100. The thickness of the liquid crystal layer 30 located between the first substrate 10 and the second substrate 20 also increases along the preset direction. The entire light modulator 100 is equivalent to a transparent prism. The incident light beam of the signal beam directed towards the light modulator 100 passes through the first substrate 10, is refracted by the liquid crystal layer 30, then reflected by the second substrate 20, and refracted again by the liquid crystal layer 30, and then passes through the first substrate 10 and exits the light modulator 100 to form an outgoing light beam; or it directly passes through the second substrate 20 and exits the light modulator 100. Since there is an angle between the plane containing the first surface and the plane containing the second surface, the light paths of the incident beam and the outgoing beam do not coincide, that is, there is an angle (∠A) between the incident beam and the outgoing beam.

[0059] In the above embodiments, the first substrate 10 is provided with a first electrode layer, and the second substrate 20 is provided with a second electrode layer 21. The first electrode layer and the second electrode layer are used to generate an electric field to drive the liquid crystal in the liquid crystal layer 30 to deflect. For example, the first electrode layer and the second electrode layer can generate a first electric field and a second electric field, where the intensity of the first electric field is greater than the intensity of the second electric field. Under the first electric field, the liquid crystal layer 30 has a first refractive index, and under the second electric field, the liquid crystal layer 30 has a second refractive index. It is understood that the signal beam will have different refraction angles after passing through the liquid crystal layer 30 with different refractive indices, so that different intensities of electric fields can be generated by adjusting the first electrode layer and the second electrode layer, thereby adjusting the angle between the incident beam and the outgoing beam, allowing the signal beam to be directed towards different target output ports.

[0060] In the optical modulator 100 provided in this application, the first substrate 10 is capable of transmitting a light beam, and the second substrate 20 is capable of reflecting or transmitting a light beam toward the first substrate 10. An angle is formed between the first surface of the first substrate 10 and the second surface of the second substrate 20. The liquid crystal layer 30 is located between the first substrate 10 and the second substrate 20, such that there is an angle between the incident light beam illuminating the optical modulator 100 and the outgoing light beam emitted from the optical modulator 100. Furthermore, a first electrode layer is provided on the first substrate 10, and a second electrode layer is provided on the second substrate 20. By adjusting the electric fields of different intensities generated by the first and second electrode layers, the refractive index of the liquid crystal layer 30 is changed, further adjusting the angle between the incident and outgoing light beams, causing the signal beam to be directed toward the target output port. The deflection of the signal beam is achieved through the principle of refraction, reducing the insertion loss of the signal beam in the optical modulator 100, thereby reducing the insertion loss during the optical switching process.

[0061] Referring again to FIG2, in some embodiments, the light modulator 100 further includes a frame 50 located between the first substrate 10 and the second substrate 20, and surrounding the liquid crystal layer 30. The frame 50 includes a first portion 51 and a second portion 52 opposite to each other in a preset direction, wherein the thickness of the first portion 51 is less than the thickness of the second portion 52. As shown, the first portion 51 and the second portion 52 are spaced apart along the preset direction, and the length of the first portion 51 in the thickness direction of the light modulator 100 is less than the length of the second portion 52 in the thickness direction of the light modulator 100. The first portion 51 connects the relatively close ends of the first substrate 10 and the second substrate 20, and the second portion 52 connects the relatively far ends of the first substrate 10 and the second substrate 20, such that there is an angle between the plane containing the first surface and the plane containing the second surface.

[0062] In the above embodiments, the included angle between the first surface and the second surface is less than or equal to 30° (∠A is less than 30°) to avoid an excessive thickness difference in the liquid crystal layer 30 located between the first substrate 10 and the second substrate 20, which would result in uneven modulation of the signal beam by the liquid crystal layer 30, preventing the deflected signal beam from reaching the target output port.

[0063] Referring to Figure 2, and in the above embodiments, the first substrate 10 and the second substrate 20 are used to generate an electric field that drives the liquid crystal in the liquid crystal layer 30 to deflect. In one embodiment, as shown in Figure 3, the first electrode layer 11 can be configured to transmit a common voltage, and correspondingly, the second electrode layer 21 can be configured to transmit a first voltage and / or a second voltage. In another embodiment, as shown in Figure 4, the first electrode layer 11 can be configured to transmit either a first voltage or a second voltage, and the second electrode layer 21 can be configured to transmit a common voltage. In both of the above embodiments, the common voltage can be a ground voltage or a fixed voltage.

[0064] Referring to Figures 2 and 3 and then to Figure 4, in an embodiment where the first electrode layer 11 is configured to transmit a common voltage, the first electrode layer 11 may include a first electrode 110, and the second electrode layer 21 may include a plurality of second electrodes 210. The second electrodes 210 extend along a preset direction, and the plurality of second electrodes 210 are arranged at intervals along a direction perpendicular to the preset direction. Each second electrode 210 may be configured to transmit a first voltage or a second voltage; for example, in two adjacent second electrodes 210, one second electrode 210 is used to transmit the first voltage, and the other second electrode 210 is used to transmit the second voltage.

[0065] The projection of the first electrode 110 in the first electrode layer 11 onto the second substrate 20 completely covers all the second electrodes 210, so that an electric field can be formed between each second electrode 210 and the first electrode 110. For example, a first electric field is formed between the second electrode 210 with a first voltage and the first electrode 110, and a second electric field is formed between the second electrode 210 with a second voltage and the first electrode 110. That is, the refractive index of the portion of the liquid crystal layer 30 located between the second electrode 210 and the first electrode 110 can be adjusted individually, and the liquid crystal layer 30 located in different regions between different second electrodes 210 and the first electrode 110 can have different refractive indices.

[0066] With the above configuration, the arrangement direction of the multiple second electrodes 210 is the same as the direction in which the signal beam is split, so that signal beams of different wavelengths can be irradiated into liquid crystal layers 30 with different regions. By adjusting the voltage of the multiple second electrodes 210, the liquid crystal layers 30 in different regions can have different refractive indices, thereby achieving different angles of deflection of signal beams of different wavelengths, and thus directing signal beams of different wavelengths toward their respective target output ports.

[0067] Meanwhile, for the individual second electrode 210, the extension direction of the second electrode 210 is perpendicular to the direction in which the signal beam is split, so that the signal beam of a certain wavelength can always be located in the liquid crystal layer 30 in the same region during the deflection process. The refractive index of the liquid crystal layer 30 in this region remains unchanged, reducing the insertion loss of the signal beam during the deflection process.

[0068] In the above embodiments, the second substrate 20 is further provided with a plurality of driving circuits, each driving circuit being electrically connected to a second electrode 210, and the driving circuit being used to provide a driving voltage to the second electrode 210. For example, in an embodiment where the second substrate 20 includes a TFT glass panel, a plurality of second electrodes 210 are disposed on the TFT glass panel, the TFTs serving as driving circuits, and each TFT being electrically connected to a second electrode 210. Through this arrangement, by individually controlling the voltage of each second electrode 210 using the driving circuits, the refractive index of the liquid crystal in the corresponding region of each second electrode 210 can be individually adjusted, thereby enabling the deflection of light beams illuminating different regions at different angles, improving the flexibility of the light modulator 100.

[0069] Referring to Figures 5 and 2, in an embodiment where the second electrode layer 21 is configured to transmit a common voltage, the first electrode layer 11 may include a plurality of first electrodes 110. The first electrodes 110 extend along a preset direction and are spaced apart in a direction perpendicular to the preset direction. Each first electrode 110 may be configured to transmit a first voltage or a second voltage; for example, in two adjacent first electrodes 110, one first electrode 110 is used to transmit the first voltage, and the other first electrode 110 is used to transmit the second voltage. The second electrode layer 21 may include a second electrode 210.

[0070] The projection of the second electrode 210 in the second electrode layer 21 onto the first substrate 10 completely covers all the first electrodes 110, so that an electric field can be formed between each first electrode 110 and the second electrode 210. For example, a first electric field is formed between the first electrode 110 with a first voltage and the second electrode 210, and a second electric field is formed between the first electrode 110 with a second voltage and the second electrode 210. That is, the refractive index of the portion of the liquid crystal layer 30 located between the first electrode 110 and the second electrode 210 can be adjusted individually, and the liquid crystal layer 30 located in different regions between different first electrodes 110 and second electrodes 210 can have different refractive indices.

[0071] With the above configuration, the arrangement direction of the multiple first electrodes 110 is the same as the direction in which the signal beam is split, so that signal beams of different wavelengths can be irradiated into liquid crystal layers 30 with different regions. By adjusting the voltage of the multiple first electrodes 110, the liquid crystal layers 30 in different regions can have different refractive indices, thereby achieving different angles of deflection of signal beams of different wavelengths, and thus directing signal beams of different wavelengths toward their respective target output ports.

[0072] Meanwhile, for the individual first electrode 110, the extension direction of the first electrode 110 is perpendicular to the direction in which the signal beam is split, so that the signal beam of a certain wavelength can always be located in the liquid crystal layer 30 in the same region during the deflection process. The refractive index of the liquid crystal layer 30 in this region remains unchanged, reducing the insertion loss of the signal beam during the deflection process.

[0073] Furthermore, compared to the above embodiment where the first electrode layer 11 is configured to a common voltage, in this embodiment the second electrode layer 21 is configured to a common voltage, and multiple second electrodes 210 are provided on the first electrode layer 11, which facilitates the projection of the signal beam from the first substrate 10 into the liquid crystal layer 30 and can further reduce the insertion loss of the signal beam in the optical modulator 100.

[0074] Referring again to Figures 2 and 3, in all the embodiments described above, the light modulator 100 may further include an alignment layer 90, which is disposed adjacent to the liquid crystal layer 30. The alignment layer 90 may define the initial alignment direction and angle of the liquid crystal molecules 31 in the liquid crystal layer 30. For example, the alignment layer 90 may be located between the first substrate 10 and the liquid crystal layer 30; or the alignment layer 90 may be located between the liquid crystal layer 30 and the second substrate 20; or the alignment layer 90 may be provided both between the first substrate 10 and the liquid crystal layer 30 and between the liquid crystal layer 30 and the second substrate 20.

[0075] In an embodiment where a reflective film 40 is provided on the side of the second substrate 20 facing the first substrate 10, the alignment layer 90 between the liquid crystal layer 30 and the second substrate 20 can be understood as the alignment layer 90 being located between the liquid crystal layer 30 and the reflective film 40.

[0076] In all the above embodiments, the liquid crystal in the liquid crystal layer 30 is a dual-frequency liquid crystal, and the first electrode layer 11 and the second electrode 210 plate are used to provide a first electric field frequency or a second electric field frequency to the dual-frequency liquid crystal. The first electric field frequency is less than the second electric field frequency. For example, the first electric field frequency is a low-frequency electric field frequency (e.g., less than 5 kHz), and the second electric field frequency is a high-frequency electric field frequency (e.g., greater than 20 kHz).

[0077] Dual-frequency liquid crystals include liquid crystals with a positive dielectric constant and liquid crystals with a negative dielectric constant. Exemplarily, in an embodiment of a dual-frequency liquid crystal with a positive dielectric constant, at a first electric field frequency, the liquid crystal molecules 31 are aligned parallel to the electric field direction (as shown in Figure 2); while at a second electric field frequency, the liquid crystal molecules 31 are aligned perpendicular to the electric field direction (as shown in Figure 6). Alternatively, at the first electric field frequency, the long axis of the liquid crystal molecules 31 extends along a first direction; at the second electric field frequency, the long axis of the liquid crystal molecules 31 extends along a second direction, wherein the first and second directions intersect. Exemplarily, the first direction is perpendicular to the electric field direction, and the second direction is parallel to the electric field direction. An embodiment of a dual-frequency liquid crystal with a negative dielectric constant is the opposite of the above embodiment and will not be described in detail here. Since the orientation of the liquid crystal molecules 31 differs at different electric field frequencies in a dual-frequency liquid crystal, the rotation of the liquid crystal molecules 31 can be accelerated by applying a frequency-varying alternating electric field to the liquid crystal in the liquid crystal layer 30. For example, by adjusting the frequency of the first electric field to the frequency of the second electric field, the liquid crystal molecules 31 are aligned perpendicularly to the direction of the electric field, or by adjusting the frequency of the second electric field to the frequency of the first electric field, the liquid crystal molecules 31 are aligned parallel to the direction of the electric field. By adjusting the frequency of the electric field, the process of the liquid crystal molecules 31 rotating to a specified angle or returning to the initial angle in the dual-frequency liquid crystal can be accelerated, thereby reducing the switching time of the light modulator 100 to achieve light exchange.

[0078] In some embodiments, the liquid crystal in the liquid crystal layer 30 can only deflect light beams with a specific polarization direction. Referring to Figures 7 and 8, in an embodiment where the wavelength selective switch 200 includes an optical fiber array 210, a grating 220, a lens group 230, and the aforementioned optical modulator 100, the wavelength selective switch 200 further includes a polarization processing device 60. The polarization processing device 60, the grating 220, the lens group 230, and the optical modulator 100 are arranged sequentially. The optical fiber array 210 includes one input port 211 and multiple output ports 212, which are spaced apart along a preset direction. The polarization processing device 60 can filter out light beams with a specific polarization direction or convert light with other polarization directions into light beams with a specific polarization direction, thereby improving the utilization efficiency of the light beam.

[0079] In the above embodiments, the light beam emitted from the fiber array 210 includes both vertically polarized beams and horizontally polarized beams. For example, if the liquid crystal only deflects the vertically polarized beam, then the vertically polarized beam can pass through the polarization processing device 60, and the horizontally polarized beam will be converted into a vertically polarized beam after passing through the polarization processing device 60.

[0080] Referring to Figure 7, in some embodiments, the lens group 230 may include only one lens. The signal beam from the input port 211 is polarized by the polarization processing device 60 to obtain a beam with a specific polarization direction. The beam then passes through the grating 220, the lens, and the optical modulator 100. By adjusting the electric field voltage, the beam is deflected, allowing the beam emitted from the input port 211 to be deflected by the optical modulator 100 and directed towards different output ports 212. The distance from the lens to the optical modulator 100 is one focal length of the lens.

[0081] Referring to Figure 8, in some embodiments, the lens group 230 includes a first lens 231 and a second lens 232. In the beam-splitting direction of the grating 220, the polarization processing device 60, the first lens 231, the grating 220, the second lens 232, and the optical modulator 100 are sequentially arranged. The polarization processing device 60 splits the signal beam into two orthogonally polarized beams, a first beam and a second beam, and then converts the polarization direction of the second beam to be the same as that of the first beam. The polarization processing device 60 can modulate the signal beam into single-polarized light, improving the utilization efficiency of the signal beam and thus reducing the insertion loss of the signal beam in the optical modulator 100. Then, the first lens 231 directs the first and second beams toward the grating 220, which disperses the first and second beams in a second direction. The beams are then converged onto the light modulator 100 by the second lens 232. The resulting beams of different wavelengths correspond to different portions of the liquid crystal layer 30 in the light modulator 100 affected by the first electrode 110 and the second electrode 210. Each portion of the liquid crystal layer 30 independently deflects the different wavelengths of the beams at different angles in the second direction. The first lens 231 and the second lens 232 have the same focal length, the distance from the first lens 231 to the second lens 232 is twice the focal length, and the distance from the second lens 232 to the light modulator 100 is one focal length.

[0082] Referring to FIG9, in some embodiments, the light modulator 100, which is based on the second substrate 20 capable of reflecting a light beam toward the first substrate 10, further includes a polarization conversion film layer 70, which is located between the second substrate 20 and the liquid crystal layer 30. In embodiments where the second substrate 20 includes a reflective layer, the polarization conversion film layer 70 is located between the reflective layer and the liquid crystal layer 30. The polarization conversion film layer 70 can convert light with other polarization directions into light with a specific polarization direction, thereby improving the utilization efficiency of the light beam.

[0083] In the above embodiment, the light beam emitted from the fiber array 210 includes both vertically polarized and horizontally polarized beams. Both vertically polarized and horizontally polarized beams can enter the optical modulator 100. For example, during the process of the signal beam hitting the second substrate 20, the liquid crystal only deflects the vertically polarized beam without affecting the horizontally polarized beam; after the signal beam passes through the polarization conversion film layer 70, the polarization conversion film layer 70 converts the horizontally polarized beam into a vertically polarized beam; during the process of the signal beam being reflected towards the first substrate 10, the liquid crystal deflects the newly converted vertically polarized beam. The two beams are deflected in the same direction and can be directed towards the same output port 212.

[0084] Referring to Figure 9 and comparing it with Figures 10, 11 and 7 and 8, in the embodiment where the optical modulator 100 includes a polarization conversion film layer 70, the wavelength selection switch 200 including the optical modulator 100 does not need to be equipped with a polarization processing device 60, which simplifies the optical path system of the wavelength selection switch 200.

[0085] Referring to FIG12, in some embodiments, the wavelength selection switch 200 further includes an optical prism 80, which has a first outer wall 81, a second outer wall 82, and a third outer wall 83. The first outer wall 81 and the third outer wall 83 are disposed opposite to each other, and both the first outer wall 81 and the third outer wall 83 are adjacent to the second outer wall 82. The fiber array 210 and the optical modulator 100 are disposed on the first outer wall 81, and the optical modulator 100 is located on the side of the fiber array 210 closer to the second outer wall 82. The grating 220 is disposed on the second outer wall 82. A reflector is formed on the third outer wall 83. The light beam input to the fiber array 210 passes through the reflector to the grating 220, and then through the reflector to the optical modulator 100. The above settings can improve the integration of the wavelength selective switch 200, make full use of the space between the grating 220, the lens and the optical modulator 100, reduce the size of the wavelength selective switch 200, and since the light path propagates in the optical prism 80, the refractive index of the medium in the light path propagation path will not be affected by the outside world, so the wavelength selective switch 200 can be non-hermetically sealed, reducing the cost of forming the wavelength selective switch 200.

[0086] Referring to Figure 13, in some embodiments, the optical cross-connection further includes a port-level optical switch 400 for realizing cross-interconnection between multiple ports. The port-level optical switch 400 provided in this application embodiment is based on an optical modulator 100 capable of transmitting light beams on a second substrate 20, and further includes an optical fiber array 210 consisting of an input port 211 and multiple output ports 212, multiple polarization control units 61, and multiple birefringent units 62. The polarization control units 61 and birefringent units 62 are located between the input port 211 and the optical modulator, and are alternately arranged along the propagation direction of the light beam input through the input port 211. The polarization control unit 61 functions similarly to the aforementioned polarization processing device 60 and polarization conversion film layer 70, and the birefringent unit 62 is formed of a birefringent crystal. For example, a signal beam emitted from input port 211 has a first polarization direction and a second polarization direction. After passing through the first polarization control unit 61, the beam with the first polarization direction can be retained. The beam with the first polarization direction passes through the first birefringence unit 62, which splits the beam with the first polarization direction into a beam with the first polarization direction and a beam with the second polarization direction. Then, the second polarization control unit 61 can filter the polarization direction, allowing the beam with the first polarization direction to pass through while converting the beam with the second polarization direction to the first polarization direction; or, allowing the beam with the second polarization direction to pass through while converting the beam with the first polarization direction to the second polarization direction, alternating in this manner. Finally, the beam enters the light modulator 100, which is capable of transmitting light, into the second substrate 20 and then into the output port 212. Through this configuration, flexible switching between multiple optical paths can be achieved.

[0087] On the other hand, referring to Figures 14 and 15, this application embodiment also provides another optical communication system, which can be an optical amplification station (OLA) for long-distance optical communication networks. The optical amplification station includes an optical amplifier (OAU) for amplifying and compensating the power of the optical signal, making up for power loss during transmission. In the above embodiment, the optical amplifier includes an optical filter 300, which may include a dynamic gain flattening filter (DGFF) to ensure a flat spectrum after amplification of the optical signal, ensuring that the power distribution of the signal beam meets requirements. The optical filter 300 may include the optical modulator 100, fiber array, and detector described above. The fiber array 210 includes an input port 211 and an output port 212. The detector 301 collects spectral power in real time. The detector 301 is connected to the optical modulator 100 and performs feedback control on the optical modulator 100 according to the spectral power. This causes light of different wavelengths in the signal beam emitted from the input port 211 to the optical modulator 100 to be deflected at different angles. This controls the light of different wavelengths to be fully coupled to the output port 212 or partially emitted to the output port 212, thereby controlling the output power of the signal beam and achieving power flatness of different channels.

[0088] In some embodiments, the light beam from the fiber array 210 passes through a reflector to a grating 220, and then through a reflector to a beam splitter 302, splitting the light beam into an incident beam that enters the optical modulator 100 and a detection beam that passes through an adjustable reflector 303 and a lens 304 and is directed toward the detector 301. The detector 301 performs feedback control on the optical modulator 100 based on the spectral power of the detection beam.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments 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 they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An optical modulator, characterized in that, include: A first substrate, wherein a first electrode layer is provided on the first substrate, and the first substrate is capable of transmitting light beams; The second substrate is disposed at a distance from the first substrate in the thickness direction of the light modulator; the second substrate is provided with a second electrode layer, and the second substrate can reflect the light beam toward the first substrate, or the second substrate can transmit the light beam. A liquid crystal layer is located between the first substrate and the second substrate; the first electrode layer and the second electrode layer are used to generate an electric field to drive the liquid crystal in the liquid crystal layer to deflect. The first substrate includes a first surface facing the second substrate, the second substrate includes a second surface facing the first substrate, the distance between the first surface and the second surface gradually increases along a preset direction, and the thickness of the liquid crystal layer also gradually increases along the preset direction; the preset direction is parallel to the second surface and perpendicular to the thickness direction of the light modulator.

2. The optical modulator according to claim 1, characterized in that, The light modulator also includes a frame located between the first substrate and the second substrate, and disposed around the liquid crystal layer; The frame includes a first part and a second part opposite to each other in the preset direction, wherein the thickness of the first part is less than the thickness of the second part.

3. The optical modulator according to claim 1 or 2, characterized in that, The angle between the first surface and the second surface is less than or equal to 30°.

4. The optical modulator according to any one of claims 1-3, characterized in that, The liquid crystal in the liquid crystal layer is a dual-frequency liquid crystal. The first electrode layer and the second electrode layer are used to provide a first electric field frequency or a second electric field frequency to the dual-frequency liquid crystal. The first electric field frequency is less than the second electric field frequency. Under the first electric field frequency, the long axis of the liquid crystal molecules of the dual-frequency liquid crystal extends along a first direction. At the second electric field frequency, the long axis of the liquid crystal molecules of the dual-frequency liquid crystal extends along the second direction, and the first direction and the second direction intersect.

5. The optical modulator according to any one of claims 1-4, characterized in that, The first electrode layer is configured to transmit a common voltage; the second electrode layer includes a plurality of second electrodes, which extend along the preset direction and are spaced apart along a direction perpendicular to the preset direction.

6. The optical modulator according to claim 5, characterized in that, The second substrate is further provided with a plurality of driving circuits, which are electrically connected to the second electrode and are used to provide driving voltage to the second electrode.

7. The optical modulator according to any one of claims 1-4, characterized in that, The first electrode layer includes a plurality of first electrodes, which extend along the preset direction and are spaced apart along a direction perpendicular to the preset direction; the second electrode layer is configured to transmit a common voltage.

8. The optical modulator according to any one of claims 1-7, characterized in that, The optical modulator further includes a polarization conversion film layer, which is located between the second substrate and the liquid crystal layer.

9. The optical modulator according to any one of claims 1-8, characterized in that, The light modulator further includes an alignment layer located between the first substrate and the liquid crystal layer, and / or, the alignment layer located between the liquid crystal layer and the second substrate.

10. A wavelength selective switch, characterized in that, The wavelength selective switch includes an optical fiber array, a grating, a lens, and an optical modulator as described in any one of claims 1-9, wherein the second substrate is capable of reflecting a light beam toward the first substrate; The grating, the lens group, and the optical modulator are arranged sequentially. The fiber array includes an input port and multiple output ports, which are spaced apart along a preset direction.

11. The wavelength selective switch according to claim 10, characterized in that, The wavelength selection switch further includes a polarization processing device, and the polarization processing device, the grating, the lens group, and the optical modulator are arranged in sequence.

12. The wavelength selective switch according to claim 10, characterized in that, The wavelength selection switch further includes an optical prism, which includes a first outer wall, a second outer wall, and a third outer wall. The first outer wall and the third outer wall are disposed opposite to each other, and both the first outer wall and the third outer wall are adjacent to the second outer wall. The fiber array and the optical modulator are disposed on the first outer wall, and the optical modulator is located on the side of the fiber array closer to the second outer wall; the grating is disposed on the second outer wall; a reflector is formed on the third outer wall; the light beam input from the fiber array passes through the reflector to the grating, and then through the reflector to the optical modulator.

13. A port-level optical switch, characterized in that, The port-level optical switch includes an input port, an output port, multiple polarization control units, multiple birefringent units, and an optical modulator as described in any one of claims 1-9, wherein the second substrate is capable of transmitting a light beam; The polarization control unit and the birefringence unit are located between the input port and the optical modulator. Multiple polarization control units and multiple birefringence units are alternately arranged along the propagation direction of the light beam input through the input port. The input port and the output port are located on both sides of the optical modulator.

14. An optical cross-connect, characterized in that, The optical cross-connect includes multiple ports and a wavelength selection switch as described in any one of claims 10-12, the wavelength selection switch being used to enable cross-connection between the multiple ports.

15. An optical cross-connect, characterized in that, The optical cross-connection includes multiple ports and a port-level optical switch as described in claim 13, wherein the port-level optical switch is used to realize cross-interconnection between the multiple ports.

16. An optical communication system, characterized in that, The optical communication system includes optical cross-connect and optical add-drop multiplexing devices as described in claim 14 or 15, wherein the optical cross-connect and the optical add-drop multiplexing devices are connected.

17. An optical filter, characterized in that, The optical filter includes an optical modulator, an optical fiber array, and a detector as described in any one of claims 1-9, wherein the optical fiber array and the optical modulator are arranged sequentially, and the detector is connected to the optical modulator.

18. An optical amplifier, characterized in that, The optical amplifier includes the optical filter as described in claim 17.

19. An optical communication system, characterized in that, The optical communication system includes the optical amplifier as described in claim 18.

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