An optical fiber facet-based metasurface light broadcaster and communication system

Abstract

The application relates to an optical fiber end surface-based metasurface light broadcaster and a communication system, comprising an optical fiber beam expander and a metasurface structure, the metasurface structure comprising a substrate arranged on the end surface of the optical fiber beam expander and a nano-brick array arranged on the substrate, the nano-brick array comprising a plurality of nano-bricks, the optical fiber beam expander amplifying a light spot in an optical fiber and then radiating the light spot into the nano-brick array; the geometric parameters of the nano-bricks of the nano-brick array are configured to perform phase modulation on polarized light transmitted by the nano-bricks to perform optical power distribution. The metasurface structure is designed on the optical fiber beam expander, the metasurface structure is integrated on the optical fiber beam expander, then the metasurface structure is connected with the optical fiber, and then the metasurface structure is integrated on the end surface of the optical fiber; the light spot in the optical fiber is amplified by the optical fiber beam expander and then radiated onto the metasurface structure, and phase modulation is performed on the metasurface structure by the nano-bricks, so that optical power distribution is realized; in this process, an alignment device is not needed, and the application reduces the complexity relative to active light regulation and passive light regulation devices.

Description

Technical Field

[0001] This application relates to the field of optical fiber device technology, and in particular to a metasurface optical broadcaster and communication system based on an optical fiber end face. Background Technology

[0002] In recent years, with socio-economic development and technological advancements, the demand for wireless communication has exploded due to broadband mobile services from consumer electronics terminals such as smartphones and tablets, as well as the interconnection of devices forming the Internet of Things. New mobile frequency bands, such as the Asia-Pacific Hertz band, are also being developed and utilized. However, the continuously exponentially growing data demand is exhausting the spectrum and capacity of wireless communication. Frequency shortages and capacity requirements have become the most intractable problems restricting the development of wireless communication. Optical frequency bands, with their greater bandwidth, can supplement wireless communication with vast spectrum resources.

[0003] Using infrared light as the frequency band for optical wireless communication can solve the above problems, but precise and independent two-dimensional control of the infrared beam is required to ensure the transmission of link signals to multiple user terminals.

[0004] Currently, two main methods are used: active optical modulation and passive optical modulation devices. Active methods include microelectromechanical system (MEMS) galvanometers and spatial light modulators. Passive methods include arrayed waveguide gratings, diffraction gratings, binary diffractive optical elements, and so on.

[0005] Regardless of the method used, the light waves in the optical fiber need to be collimated and the angle adjusted before being incident on the optical control device, which undoubtedly increases the complexity and integration of the system. Summary of the Invention

[0006] This application provides a metasurface optical broadcaster and communication system based on an optical fiber endface, which integrates the metasurface structure on the optical fiber endface, eliminating the need for alignment devices and thus reducing complexity.

[0007] In a first aspect, a metasurface optical broadcaster based on an optical fiber endface is provided, comprising:

[0008] An optical fiber expander and a metasurface structure, wherein the metasurface structure includes a substrate disposed on one end face of the optical fiber expander and a nanobrick array disposed on the substrate, the nanobrick array comprising a plurality of nanobricks, and the optical fiber expander is used to amplify the light spot in the optical fiber and then direct it into the nanobrick array.

[0009] The geometric parameters of the nanobricks in the nanobrick array are configured to phase modulate the polarized light transmitted through the nanobricks in order to distribute optical power.

[0010] In some embodiments, the metasurface structure is a geometrically phased metasurface structure, wherein the geometric parameters include the rotation angle, length, width, height, and period of the nanobrick, and the period is a subwavelength scale.

[0011] In some embodiments, the metasurface structure is a phase-transfer metasurface structure, and the geometric parameters include the length, width, height, and period of the nanobrick, with the period being a subwavelength scale.

[0012] In some embodiments, the metasurface structure is a metasurface structure combining geometric phase and transmission phase, wherein the geometric parameters include the rotation angle, length, width, height and period of the nanobrick, and the period is a subwavelength scale.

[0013] In some embodiments, the polarized light is circularly polarized light, and the metasurface light broadcaster further includes a polarization controller for modulating light in the optical fiber into the circularly polarized light.

[0014] In some embodiments, the length, width, and height of the nanobrick are 600 nm, 280 nm, and 570 nm, respectively.

[0015] In some embodiments, the period is 900 nm.

[0016] Secondly, a metasurface communication system based on an optical fiber endface is provided, which includes a metasurface optical broadcaster, a laser, a modulator, an optical amplifier, and an optical fiber as described above, wherein the laser, modulator, optical amplifier, optical fiber, and optical fiber expander are connected in sequence.

[0017] In some embodiments, the optical fiber is a single-mode fiber or a multimode fiber;

[0018] And / or, the laser is a semiconductor laser.

[0019] In some embodiments, the modulator is a Mach-Zehnder modulator;

[0020] And / or, the optical amplifier is an erbium-doped fiber amplifier.

[0021] The beneficial effects of the technical solution provided in this application include:

[0022] This application provides a metasurface optical broadcaster and communication system based on an optical fiber endface. A metasurface structure is designed on an optical fiber expander, integrating the metasurface structure onto the optical fiber expander and then connecting it to the optical fiber. This integrates the metasurface structure onto the optical fiber endface. In use, the light spot in the optical fiber is amplified by the optical fiber expander and then projected onto the metasurface structure on the endface. Phase modulation is achieved through nanobricks, thereby realizing optical power distribution. This process does not require an alignment device, and compared to active and passive optical modulation devices, this application reduces complexity. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram of a metasurface optical broadcaster based on an optical fiber end face provided in an embodiment of this application;

[0025] Figure 2 A schematic diagram of nanobricks provided in the embodiments of this application;

[0026] Figure 3 A light spot distribution diagram provided for an embodiment of this application;

[0027] Figure 4 This is a schematic diagram of a metasurface communication system based on an optical fiber end face, provided in an embodiment of this application.

[0028] In the diagram: 1. Fiber optic expander; 2. Nanobrick array; 3. Nanobrick; 4. Fiber optic cable. Detailed Implementation

[0029] 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.

[0030] See Figure 1As shown, this application embodiment provides a metasurface optical broadcaster based on an optical fiber end face. The metasurface optical broadcaster includes an optical fiber expander 1 and a metasurface structure. The metasurface structure includes a substrate disposed on one end face of the optical fiber expander 1 and a nanobrick array 2 disposed on the substrate. The nanobrick array 2 includes a plurality of nanobricks 3. The optical fiber expander 1 is used to amplify the light spot in the optical fiber 4 and then transmit it into the nanobrick array 2. The geometric parameters of the nanobricks 3 in the nanobrick array 2 are configured to perform phase modulation on the polarized light transmitted through the nanobricks 3 in order to perform optical power distribution.

[0031] Since the cross-sectional area of ​​the fiber end face is too small to accommodate a metasurface structure, the fiber expander 1 connected to fiber 4 can uniformly amplify the light spot in fiber 4 and then project it onto the metasurface structure at the end face. Clearly, one end of the fiber expander 1 is the larger end, connected to the metasurface structure, and the other end is the smaller end, connected to fiber 4.

[0032] The geometric parameters of the nanobrick 3 are configured to: phase modulate the polarized light transmitted through the nanobrick 3 to distribute the optical power, and finally transmit the optical signal to different locations in space for reception by different users.

[0033] The metasurface optical broadcaster provided in this application has a metasurface structure designed on an optical fiber expander, which is then connected to the optical fiber. This allows the metasurface structure to be integrated on the end face of the optical fiber. In use, the light spot in the optical fiber is amplified by the optical fiber expander and then projected onto the metasurface structure on the end face. Phase modulation is achieved through nanobricks, thereby realizing optical power distribution. This process does not require an alignment device, and compared with active and passive optical modulation devices, this application reduces complexity.

[0034] There are several ways to design metasurface structures, such as geometric phase, transport phase, and a combination of geometric phase and transport phase.

[0035] If a width response to multiple wavelengths is required, the metasurface structure can be designed using a geometric phase approach. If a width response to a single wavelength is required, the metasurface structure can be designed using a transmission phase approach.

[0036] If a more flexible light field design is required, allowing for simultaneous control of multiple parameters, such as light field mode control, then a combination of two phase design methods can be used.

[0037] As an example, a metasurface structure is designed using a geometric phase approach, meaning that the metasurface structure is a geometric phase metasurface structure. In this case, the geometric parameters include the rotation angle, length, width, height, and period of the nanobrick 3, and the period is a subwavelength scale.

[0038] Among them, the corners are as follows Figure 2 As shown, the nanobricks in the metasurface structure have a long side of L, a wide side of W, a height of H, and a period of C. The angle between the long side and the x-axis is... That is, the corner of the nanobrick.

[0039] Each corner corresponds to an orientation of the nanobrick, which in turn corresponds to a phase. Therefore, the corner of the nanobrick can be adjusted to adjust the phase.

[0040] Regarding the design of the geometric phase, it is necessary to ensure that the incident light is circularly polarized. According to the Jones matrix, when the nanobrick is equivalent to a half-wave plate, the rotation direction of the outgoing circularly polarized light is not only opposite to the rotation direction of the incident circularly polarized light, but also produces a... The phase delay is twice the angle of the nanobrick. Therefore, by controlling the angle of each nanobrick, the position and phase of the incident light can be controlled point by point.

[0041] Therefore, the length, width, height, and period of the nanobrick are configured to make the nanobrick equivalent to a half-wave plate.

[0042] To make the nanobrick function equivalent to a half-wave plate, Comsol or CSTstudio can be used for simulation. During the simulation, periodic boundary conditions are applied in the x and y directions, and it is assumed that all nanobricks are oriented in the same direction. Since the loss in the communication band is essentially zero at 1550nm, the center wavelength is set to 1550nm. Left-handed circularly polarized light is input to the input port, and both left-handed and right-handed circularly polarized light are received at the receiving port. Through parameter simulation, the dimensions of the nanobrick can be obtained: a length of 600nm, a height of 570nm, a width of 280nm, and a period of 900nm. At this point, the metasurface structure exhibits excellent polarization conversion efficiency and transmittance.

[0043] Accordingly, when the incident polarized light is circularly polarized, the metasurface light broadcaster also includes a polarization controller, which is used to modulate the light in the fiber 4 into circularly polarized light.

[0044] Taking a metasurface light broadcaster with a splitting ratio of 1:64 as an example, its light wave splitting effect is as follows: Figure 3 As shown, after passing through an optical fiber expander and a metasurface optical broadcaster, the light in the optical fiber generates an 8×8 beam array in the far field, distributing the optical signal one-to-many to different users in space. Because of centrosymmetry, the diffraction fields of the two circularly polarized lights with different rotation directions overlap, and beam splitting is independent of polarization. That is, if a symmetrical beam is generated, there is no need to adjust the polarization of the light in the optical fiber.

[0045] As another example, a metasurface structure is designed using a transport phase approach. This means the metasurface structure is a transport phase metasurface structure. In this case, the geometric parameters include the length, width, height, and period of the nanobrick 3, with the period being on a subwavelength scale. Phase adjustment can be achieved by optimizing the length, width, height, and period of the nanobrick 3.

[0046] As another example, a metasurface structure is designed using a combination of geometric phase and transmission phase. That is, the metasurface structure is a combination of geometric phase and transmission phase. In this case, the geometric parameters include the rotation angle, length, width, height, and period of the nanobrick 3, with the period being on a subwavelength scale. Phase modulation is achieved in two dimensions by combining the rotation angle with the length, width, height, and period.

[0047] See Figure 4 As shown, this application embodiment also provides a metasurface communication system based on an optical fiber endface. As a typical application architecture, the metasurface communication system includes the aforementioned metasurface optical broadcaster based on an optical fiber endface, a laser, a modulator, an optical amplifier, and an optical fiber 4. The laser, modulator, optical amplifier, optical fiber 4, and optical fiber expander 1 are connected in sequence.

[0048] First, a laser emits light waves with a wavelength of 1550nm. Then, a signal carrying data is modulated onto the optical signal, which is then amplified by an optical amplifier. The optical signal travels several kilometers through the optical fiber before entering the indoor fiber optic link.

[0049] After entering the indoor fiber optic link, the light waves coming out of the fiber optic cable are transmitted to users in different locations indoors via a metasurface optical broadcaster located on the end face of the fiber optic cable.

[0050] Among them, fiber 4 can be selected in different types according to actual needs. For example, fiber 4 can be single-mode fiber or multi-mode fiber.

[0051] Lasers can be selected from different types according to actual needs. For example, a semiconductor laser can be used as an example.

[0052] The modulator can be selected from different types according to actual needs. For example, as an example, a Mach-Zehnder modulator is used.

[0053] Optical amplifiers can be selected from different types according to actual needs. For example, as an example, an erbium-doped fiber amplifier can be used as an optical amplifier.

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

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

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

Claims

1. A metasurface communication system based on an optical fiber endface, characterized in that, It includes a metasurface optical broadcaster based on an optical fiber endface, a laser, a modulator, an optical amplifier, and an optical fiber (4). The laser, modulator, optical amplifier, optical fiber (4), and optical fiber expander (1) are connected in sequence. The laser is a semiconductor laser, the optical fiber (4) is a single-mode fiber or a multimode fiber, the modulator is a Mach-Zehnder modulator, and the optical amplifier is an erbium-doped fiber amplifier. The metasurface optical broadcaster based on an optical fiber endface includes: The fiber expander (1) and metasurface structure, wherein the metasurface structure includes a substrate disposed on one end face of the fiber expander (1) and a nanobrick array (2) disposed on the substrate, wherein the nanobrick array (2) includes a plurality of nanobricks (3), and the fiber expander (1) is used to amplify the light spot in the fiber (4) and then inject it into the nanobrick array (2). The geometric parameters of the nanobricks (3) in the nanobrick array (2) are configured such that the polarized light transmitted through the nanobricks (3) is phase-modulated to distribute the optical power. The metasurface structure is a metasurface structure that combines geometric phase with transmission phase. The geometric parameters include the rotation angle, length, width, height and period of the nanobrick (3), and the period is a subwavelength scale. The length, width and height of the nanobrick (3) are 600nm, 280nm and 570nm respectively, and the period is 900nm.

2. The metasurface communication system based on optical fiber endface as described in claim 1, characterized in that: The polarized light is circularly polarized light, and the metasurface light broadcaster also includes a polarization controller, which is used to modulate the light in the optical fiber (4) into the circularly polarized light.

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