Optical device and free-space optical communication system

Abstract

An optical device and a free-space optical communication system, relating to the field of optical communications. The optical device comprises a transmitting module, a receiving module, an optical splitting module, and an optical antenna module. The optical splitting module is separately connected to the transmitting module, the receiving module, and the optical antenna module. The optical splitting module is used for, on the basis of a splitting function for optical signals of different wavelengths, outputting a single-mode optical signal outputted by the transmitting module to the optical antenna module, and for outputting a multi-mode optical signal received by the optical antenna module to the receiving module. The wavelength of the single-mode optical signal is different from the wavelength of the multi-mode optical signal. The optical antenna module transmits the single-mode optical signal and receives the multi-mode optical signal. The receiving module processes the multi-mode optical signal. On the basis of the structure, the transmit-receive coaxiality of the optical device is more easily resistant to adverse environmental influences due to the optical splitting module being built inside the optical device, thereby enhancing the stability of the transmit-receive coaxiality.

Description

An optical device and a free-space optical communication system

[0001] This application claims priority to Chinese Patent Application No. 202411697725.0, filed on November 22, 2024, entitled "An Optical Device and a Free-Space Optical Communication System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technology, and more specifically, to an optical device and a free-space optical communication system. Background Technology

[0003] Free-space optical communication (FSO) is a communication technology that uses laser light as the carrier and free space as the transmission channel. In practical applications, atmospheric turbulence can cause laser beam fragmentation, flickering, broadening, and fluctuations in the angle of arrival. To mitigate the adverse effects of atmospheric turbulence, FSO systems can employ multimode fiber to receive the laser beam. Furthermore, because strict control of the laser divergence angle is required, FSO systems typically use single-mode fiber for laser transmission.

[0004] Since an FSO system is a full-duplex system, signal transmission and reception must be in the same direction, corresponding to the coaxiality of the transmitting and receiving axes within the FSO system. Current FSO systems mostly use dichroic mirrors to achieve signal splitting / combining / receiving in the spatial optical path. This method is difficult to assemble and adjust, and is easily affected by harsh environmental conditions such as high and low temperatures and vibrations in outdoor scenarios, which in turn affects the stability of the FSO system's transmit-receive coaxiality. Therefore, improving the stability of the transmit-receive coaxiality of FSO systems is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] This application provides an optical device and a free-space optical communication system that can improve the stability of the transmit and receive coaxiality of the FSO system.

[0006] In a first aspect, an optical device is provided, comprising: a transmitting module, a receiving module, a beam splitting module, and an optical antenna module. The beam splitting module is connected to the transmitting module, the receiving module, and the optical antenna module, respectively. The beam splitting module is used to: output a single-mode optical signal output from the transmitting module to the optical antenna module based on its beam splitting function for optical signals of different wavelengths, and output a multimode optical signal received by the optical antenna module to the receiving module, wherein the wavelength of the single-mode optical signal is different from the wavelength of the multimode optical signal; the optical antenna module is used to transmit the single-mode optical signal and receive the multimode optical signal, and the receiving module is used to process the multimode optical signal.

[0007] In the above structure, the optical device routes different optical signals by splitting them using a beam splitter module. Specifically, the beam splitter module outputs the single-mode optical signal from the transmitting module to the optical antenna module, and outputs the multi-mode optical signal received by the optical antenna module to the receiving module. In other words, the optical device integrates signal transmission and reception through the beam splitter module. Thus, based on this structure, the coaxiality of the transmission and reception of the optical device is more resistant to adverse environmental influences (such as high and low temperatures and vibrations) because the beam splitter module is built into the optical device, thereby improving the stability of the coaxiality. Furthermore, this structure eliminates the need for coaxial alignment, solving the problem of high assembly difficulty that hinders the mass production of optical devices. Additionally, compared to dichroic mirrors, beam splitters offer better long-term stability, which also contributes to improved coaxiality stability.

[0008] Compared to existing solutions that achieve coaxial signal transmission and reception using a dichroic mirror architecture, employing a more stable beam splitter module to process optical signals of different wavelengths not only reduces assembly and adjustment complexity but also ensures that the FSO system is less susceptible to harsh environments such as high and low temperatures and vibrations when used in external environments, thereby guaranteeing the stability of the FSO system's transmission and reception coaxiality. Furthermore, the use of single-mode transmission and multi-mode reception enhances the FSO system's resistance to atmospheric turbulence.

[0009] In some implementations of the first aspect, the beam splitter is connected to the transmitting module via a single-mode fiber, to the receiving module via a multimode fiber, and to the optical antenna module via a multi-clad fiber. Thus, based on this structure, both single-mode optical signal transmission and multimode optical signal reception can be achieved.

[0010] In some implementations of the first aspect, the optical device further includes a mode field matcher disposed between the optical antenna module and the beam splitter module. Thus, by placing the mode field matcher between the beam splitter module and the optical antenna module, it is beneficial to match the transmit mode field and the receive mode field, ensuring that the transmitted beam corresponding to the single-mode optical signal meets the divergence angle and transmit aperture requirements at the exit pupil (i.e., the emission point) of the optical antenna module. Simultaneously, it ensures that the received spot of the multimode optical signal does not exceed the core diameter of the multimode optical fiber, thus guaranteeing high reception efficiency.

[0011] In some implementations of the first aspect, the mode field matcher includes an optical transformation component for controlling the optical field characteristics of the optical signal transmitted by the optical antenna module. By incorporating the optical transformation component, this increases the optical spread, ensuring that the emitted beam of the single-mode optical signal meets the divergence angle and emission aperture requirements at the exit pupil (i.e., the emission point) of the optical antenna module. It also reduces the impact on the beam pattern of multimode optical signals passing through atmospheric turbulence channels, thereby improving reception efficiency.

[0012] In some implementations of the first aspect, the mode field matcher includes a fiber microlens disposed on the end face of a multi-clad fiber, and the beam splitter is connected to the optical antenna module via the multi-clad fiber. Thus, by using the fiber microlens, for single-mode transmission, the fiber microlens can reduce the divergence angle of the single-mode optical signal, thereby increasing the focal length of the optical system in the transmission path and matching the core size and numerical aperture (NA) of the multi-mode fiber; for multi-mode reception, the fiber microlens can increase the receiving field of view (describing the angular range that the optical system can receive; i.e., if the incident angle of the multi-mode optical signal exceeds the receiving field of view of the multi-mode fiber, it cannot enter the multi-mode fiber) for multi-mode optical signals.

[0013] In some implementations of the first aspect, the mode field matcher includes a fiber taper microlens disposed on the fiber end face of a multi-clad fiber, and the beam splitter is connected to the optical antenna module through the multi-clad fiber.

[0014] In some implementations of the first aspect, the mode field matcher comprises a multi-clad fiber based on a core-expanded fiber. Thus, by expanding the core of the multi-clad fiber, the core diameter of the multi-clad fiber can be increased, thereby increasing the focal length of the optical device's transmission system. Furthermore, since the thermal expansion operation has minimal impact on the cladding of the multi-clad fiber, the focal length of the optical device's transmission system can also be matched to the diameter of the inner cladding of the multi-clad fiber and the NA (Mode Field).

[0015] In some implementations of the first aspect, the beam splitting module includes at least one of the following: a thin-film filter, a fused biconical taper fiber, or a fiber Bragg grating. Thus, embodiments of this application can support beam splitting of optical signals of different wavelengths.

[0016] In some implementations of the first aspect, the beam splitting function for optical signals of different wavelengths includes: transmitting a single-mode optical signal and reflecting a multimode optical signal; or reflecting a single-mode optical signal and transmitting a multimode optical signal. This enables the beam splitting of optical signals of different wavelengths.

[0017] In some implementations of the first aspect, the optical device further includes a single-mode wavelength division multiplexer (WDM) and a multi-mode wavelength division multiplexer (MWDM). The single-mode WDM is positioned between the transmitting module and the beam splitting module, and the multi-mode WDM is positioned between the receiving module and the beam splitting module. By placing the single-mode WDM between the transmitting module and the beam splitting module, when the transmitting module outputs multiple single-mode optical signals of different wavelengths, the single-mode WDM can perform multiple-way combining of these single-mode optical signals, thereby supporting applications in multi-wavelength scenarios. Similarly, by placing the multi-mode WDM between the receiving module and the beam splitting module, when the beam splitting module outputs a composite multi-mode optical signal composed of multiple multi-mode optical signals of different wavelengths, the multi-mode WDM can perform multiple-way splitting of this composite multi-mode optical signal, thereby supporting applications in multi-wavelength scenarios.

[0018] In some implementations of the first aspect, the optical device further includes a fiber optic filter disposed between the receiving module and the splitting module. This achieves isolation between signal transmission and signal reception, meaning the receiving module will not receive stray light returned from the transmitted signal.

[0019] In some implementations of the first aspect, the optical device further includes an optical amplifier disposed between the transmitting module and the beam splitting module. This enables power amplification of the single-mode optical signal.

[0020] In some implementations of the first aspect, the optical device is applied to free-space optical communication scenarios via atmospheric channels.

[0021] Specifically, atmospheric channels refer to communication channels through which lasers transmit information in the atmospheric medium. These include communication between satellites and ground stations, communication between ground stations, and communication between aerial drones / hot air balloons, etc. When the aforementioned optical devices are applied to free-space optical communication scenarios via atmospheric channels, this can improve the stability of the transceiver coaxiality of the optical devices in atmospheric channel application scenarios.

[0022] Secondly, a free-space optical communication system is provided, comprising a first optical device, which includes the optical device described in the first aspect and any possible implementation thereof. The first optical device is configured to transmit a first single-mode optical signal to a second optical device and receive a second multimode optical signal, wherein the second multimode optical signal is an optical signal obtained based on the second single-mode optical signal transmitted by the second optical device, and the wavelength of the first single-mode optical signal is different from the wavelength of the second single-mode optical signal.

[0023] In some implementations of the second invention, the free-space optical communication system further includes the aforementioned second optical device, which includes the optical device described in the first aspect and any possible implementation of the first aspect.

[0024] For a description of the beneficial effects of the second and third aspects, please refer to the description of the beneficial effects of the first aspect, which will not be repeated here. Attached Figure Description

[0025] Figure 1 is a schematic diagram of the architecture of the FSO system 100.

[0026] Figure 2 is a schematic diagram of the architecture of the FSO system 200 according to an embodiment of this application.

[0027] Figure 3 is a schematic diagram of the beam splitter module.

[0028] Figure 4 is a schematic diagram of the structure of port 1, port 2 and port 3.

[0029] Figure 5 is a schematic diagram of the principle of spectral dispersion.

[0030] Figure 6 is another schematic diagram of the principle of spectral dispersion.

[0031] Figure 7 is a schematic diagram of the deployment of the optical conversion component.

[0032] Figure 8 is a schematic diagram of the deployment of fiber optic microlenses.

[0033] Figure 9 is a schematic diagram of different shapes of fiber optic microlenses.

[0034] Figure 10 is a schematic diagram of a multi-clad optical fiber based on expanded core fiber.

[0035] Figure 11 is a schematic diagram of an optical device.

[0036] Figure 12 is a schematic diagram of another structure of the optical device. Detailed Implementation

[0037] To facilitate understanding of the embodiments of this application, the following points will be explained first.

[0038] I. Unless otherwise specified or in case of logical conflict, the terms and / or descriptions in different embodiments of this application are consistent and can be referenced in each other. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0039] II. The various numerical designations used in this application are merely for descriptive convenience and do not limit the scope of protection of this application. The magnitude of the serial numbers used in this application does not imply the order of execution; the execution order of each process should be determined by its function and internal logic. For example, the terms "first (1)", "second (2)", "third (3)" and other various terminology (if present) in the specification, claims, and drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order. The data used in this way can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein.

[0040] Furthermore, any embodiment or design described in this application as "exemplary" or "for example" should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner for ease of understanding.

[0041] 3. The terms “comprising” and “having” and any variations thereof are intended to cover non-exclusive inclusion, for example, a system, product or device that includes a series of steps or units is not necessarily limited to those units that are explicitly listed, but may include other units that are not explicitly listed or that are inherent to such products or devices.

[0042] The optical device and free-space optical communication system described in this application can be applied to various free-space optical communication scenarios, including but not limited to: space optical communication between satellites and ground stations; space optical communication between aircraft, hot air balloons, drones, etc., or between them and the ground; and space optical communication scenarios such as backhaul from ground-based wireless base stations.

[0043] For ease of description, the relevant technical terms will be described first below.

[0044] 1. Single-mode light and multi-mode light

[0045] A light wave with a certain frequency, a certain polarization state, and a certain spatial distribution of intensity is called a mode or wave type of light wave. The mode discussed in this application is the transverse mode of light, which describes the intensity distribution pattern on the cross-section of the light wave during transmission. Therefore, single-mode light is a light wave with one mode (usually the fundamental mode, with a Gaussian intensity distribution on the cross-section of the beam), while multimode light is a light wave with at least two modes.

[0046] 2. Single-mode fiber

[0047] Single-mode fiber refers to optical fiber that allows the transmission of only one mode of light wave, or single-mode fiber is used to transmit single-mode light.

[0048] 3. Multimode fiber

[0049] Multimode fiber refers to optical fiber that allows the simultaneous transmission of multiple modes of light waves, or multimode fiber is used to transmit multimode light.

[0050] 4. Multi-clad optical fiber

[0051] Multiclad fiber refers to optical fiber capable of transmitting both multimode and single-mode light. Multiclad fiber mainly consists of a core, a coating, and at least two cladding layers. The core transmits single-mode light, and at least one cladding layer transmits multimode light. For example, double-clad fiber includes a core, inner cladding, outer cladding, and a coating; the core transmits single-mode light, and the inner cladding transmits multimode light. As another example, triple-clad fiber includes a core, inner cladding, middle cladding, outer cladding, and a coating; the core transmits single-mode light, and the inner and middle cladding layers transmit multimode light.

[0052] Figure 1 is a schematic diagram of the architecture of the FSO system 100. As shown in Figure 1, the FSO system 100 includes: a transmitting module 1, a receiving module 1, an optical antenna module 1, an optical antenna module 2, a transmitting module 2, and a receiving module 2. The transmitting module 1, receiving module 1, and optical antenna module 1 can be understood as components of the A-end device, and the transmitting module 2, receiving module 2, and optical antenna module 2 can be understood as components of the B-end device. Signal transmission between the A-end device and the B-end device occurs through a free-space channel.

[0053] In the FSO system 100, the transmitting module is used for outputting optical signals, the receiving module is used for processing optical signals, and the optical antenna module is used for both transmitting and receiving optical signals. For example, optical antenna module 1 transmits optical signal 1 output from transmitting module 1 to a free-space channel, and optical antenna module 2 receives optical signal 1 from the free-space channel and transmits it to receiving module 2, where receiving module 2 processes optical signal 1. As another example, optical antenna module 2 transmits optical signal 2 output from transmitting module 2 to a free-space channel, and optical antenna module 1 receives optical signal 2 from the free-space channel and transmits it to receiving module 1, where receiving module 1 processes optical signal 2.

[0054] As described in the background section, FSO systems often employ dichroic mirrors to achieve signal splitting / combining in the spatial optical path. This method is difficult to assemble and adjust, and is easily affected by harsh environmental conditions such as high and low temperatures and vibrations in outdoor scenarios, which in turn affects the stability of the FSO system's transmit-receive coaxiality. Therefore, this application provides an optical device and a free-space optical communication system that can support and improve the stability of the FSO system's transmit-receive coaxiality. See Figure 2 for details.

[0055] Figure 2 is a schematic diagram of the architecture of the FSO system 200 according to an embodiment of this application. As shown in Figure 2, the FSO system 200 includes: a transmitting module 1, a receiving module 1, a beam splitting module 1, an optical antenna module 1, an optical antenna module 2, a beam splitting module 2, a transmitting module 2, and a receiving module 2. The transmitting module 1, the receiving module 1, and the optical antenna module 1 are all connected to the beam splitting module 1, and the transmitting module 2, the receiving module 2, and the optical antenna module 2 are all connected to the beam splitting module 2. The transmitting module is used to output single-mode optical signals, the receiving module is used to process multimode optical signals, the optical antenna module is used to transmit single-mode optical signals and receive multimode optical signals, and the beam splitting module is used to split the single-mode optical signals and multimode optical signals.

[0056] In the FSO system 200, the transmitting module 1, receiving module 1, beam splitting module 1, and optical antenna module 1 are components of optical device 1. That is, optical device 1 includes: transmitting module 1, receiving module 1, beam splitting module 1, and optical antenna module 1 (and may also include other components). The transmitting module 2, receiving module 2, beam splitting module 2, and optical antenna module 2 are components of optical device 2. That is, optical device 2 includes: transmitting module 2, receiving module 2, beam splitting module 2, and optical antenna module 2 (and may also include other components). Alternatively, the FSO system 200 includes optical device 1 and optical device 2, and signal transmission between optical device 1 and optical device 2 occurs through a free-space channel. For example:

[0057] In one example, optical communication device 1 sends a single-mode optical signal 1 to optical device 2 through optical antenna module 1. The single-mode optical signal 1 is converted into a multi-mode optical signal 1 after transmission through a free space channel. Optical device 2 receives the multi-mode optical signal 1 through optical antenna module 2.

[0058] In one example, optical device 2 sends a single-mode optical signal 2 to optical device 1 through optical antenna module 2. The single-mode optical signal 2 is converted into a multi-mode optical signal 2 after being transmitted through a free space channel. Optical device 1 receives the multi-mode optical signal 2 through optical antenna module 1.

[0059] In the above example, the wavelength of single-mode optical signal 1 is the same as the wavelength of multimode optical signal 1, the wavelength of single-mode optical signal 2 is the same as the wavelength of multimode optical signal 2, and the wavelength of single-mode optical signal 1 is different from the wavelength of single-mode optical signal 2. That is, the wavelength of the optical signal emitted by optical device 1 (not limited to optical device 2) (which is single-mode optical signal 1) is different from the wavelength of the received optical signal (which is multimode optical signal 2). Optical device 1 (not limited to optical device 2) can output single-mode optical signal 1 to optical antenna module 1 and output multimode optical signal 2 to receiving module 1 through beam splitting module 1 (based on the beam splitting function of beam splitting module 1 for optical signals of different wavelengths). For ease of description, the beam splitting module 1 is used as an example below, and can be seen in Figure 3.

[0060] Figure 3 is a schematic diagram of the structure of the beam splitter module 1. As shown in Figure 3, the beam splitter module 1 includes port 1, port 2, port 3, and a beam splitting component. Port 1 is connected to the transmitting module 1 and is used to acquire the single-mode optical signal 1 output by the transmitting module 1. Port 2 is connected to the receiving module 1 and is used to transmit the multimode optical signal 2 to the receiving module 1. Port 3 is connected to the optical antenna module 1 and is used to transmit the single-mode optical signal 1 to the optical antenna module 1 and acquire the multimode optical signal 2 from the optical antenna module 1. The beam splitting component is connected to ports 1, 2, and 3 respectively. The content shown in Figure 3 is for illustrative purposes only and is not intended as a final limitation.

[0061] The beam splitter module 1 can, based on a beam splitter component or on the beam splitting function of optical signals of different wavelengths, output the single-mode optical signal 1 acquired through port 1 to port 3, and output the multimode optical signal 2 acquired through port 3 to port 2; or, the beam splitter component can perform beam splitting processing on optical signals of different wavelengths. For example:

[0062] For example, port 1 is connected to the transmitting module 1, and port 3 is connected to the optical antenna module 1. The transmitting module 1 transmits a single-mode optical signal 1 to the beam splitting module 1 through port 1. The beam splitting module 1 outputs the single-mode optical signal 1 to port 3 through the beam splitting component to split different wavelengths, and outputs the single-mode optical signal 1 to the optical antenna module 1 through port 3.

[0063] For example, port 2 is connected to receiving module 1, and port 3 is connected to optical antenna module 1. Optical antenna module 1 transmits multimode optical signal 2 to beam splitting module 1 through port 3. Beam splitting module 1 outputs multimode optical signal 2 to port 2 through beam splitting component to split different wavelengths, and outputs multimode optical signal 2 to receiving module 1 through port 2.

[0064] Figure 3 is for illustrative purposes only and is not intended as a final limitation.

[0065] In summary, the optical device routes different optical signals by splitting them using a beam splitter module. Specifically, the beam splitter module outputs the single-mode optical signal from the transmitting module to the optical antenna module, and outputs the multi-mode optical signal received by the optical antenna module to the receiving module. In other words, the optical device achieves integrated signal transmission and reception through the beam splitter module. Based on this structure, the coaxiality of the transmission and reception of the optical device is more resistant to adverse environmental influences (such as high and low temperatures and vibrations) because the beam splitter module is built into the internal structure, thus improving the stability of the coaxiality. Furthermore, this structure eliminates the need for assembly and adjustment of the transmission and reception coaxiality, solving the problem of high assembly and adjustment difficulty that hinders the mass production of optical devices. Additionally, compared to dichroic mirrors, beam splitters offer better long-term stability, which also contributes to improved coaxiality stability.

[0066] Compared to existing schemes that achieve coaxial signal transmission and reception using a dichroic mirror architecture, employing a more stable (e.g., more resistant to vibration and temperature changes) beam splitter module to process optical signals of different wavelengths not only reduces assembly and adjustment complexity but also ensures that the FSO system is less susceptible to harsh environments such as high and low temperatures and vibrations when used in external environments, thus guaranteeing the stability of the FSO system's transmission and reception coaxiality. Furthermore, the use of single-mode transmission and multi-mode reception also enhances the FSO system's resistance to atmospheric turbulence.

[0067] One possible implementation is that the optical splitter module 1 outputs single-mode optical signal 1 to the optical antenna module and outputs multi-mode optical signal 2 to the receiving module, including:

[0068] Based on the optical effect 1 of the beam splitter on the single-mode optical signal 1, the single-mode optical signal 1 is output to port 3 (i.e., optical antenna module 1);

[0069] Based on the optical function 2 of the beam splitter for the multimode optical signal 2, the multimode optical signal 2 is output to port 2 (i.e., receiving module 1). The optical function 1 is different from the optical function 2.

[0070] For example, optical action 1 is transmission and optical action 2 is reflection; or, optical action 1 is reflection and optical action 2 is transmission. In this way, it is possible to perform spectral splitting of optical signals of different wavelengths.

[0071] In Figure 3, port 1 is connected to the transmitting module 1 via a single-mode fiber, port 2 is connected to the receiving module 1 via a multimode fiber, and port 3 is connected to the optical antenna module 1 via a multi-clad fiber, thereby acquiring the corresponding optical signal. Alternatively, the splitter module 1 is linked to the transmitting module 1 via a single-mode fiber, the splitter module 1 is linked to the receiving module 1 via a multimode fiber, and the splitter module 1 is connected to the optical antenna module 1 via a multi-clad fiber.

[0072] One possible implementation is that port 1 comprises single-mode fiber, port 2 comprises multimode fiber, and port 3 comprises multi-clad fiber. Based on this structure, it is possible to transmit single-mode optical signals and receive multimode optical signals. See Figure 4 for a detailed description.

[0073] Figure 4 is a schematic diagram of ports 1, 2, and 3. As shown in Figure 4, the pigtail of the single-mode fiber connects to the transmitting module 1 through port 1. The pigtail of the multimode fiber connects to the receiving module 1 through port 2. The pigtail of the multi-clad fiber connects to the optical antenna module 1 through port 3. Furthermore, the single-mode fiber, multimode fiber, and multi-clad fiber are all connected to the beam splitter. Based on this structure, optical signal transmission can be achieved.

[0074] Ports 1, 2, and 3 shown in Figure 4 are for illustrative purposes only. In actual implementation, port 1, port 2, and port 3 can be implemented in other ways. For example, port 1 can be a single-mode waveguide port used to acquire the single-mode optical signal 1 output by the transmitting module 1; port 2 can be a beam splitter waveguide port used to output the single-mode optical signal 1 and acquire the multimode optical signal 2; and port 3 can be a multimode waveguide port used to output the multimode optical signal 2.

[0075] One possible implementation is that the beam splitting component (or beam splitting module) includes one or more of the following:

[0076] Thin-film filters (unlimited quantity);

[0077] Fused tapered fiber (no quantity limit); or,

[0078] Fiber Bragg gratings (quantity not limited).

[0079] Thus, the embodiments of this application can support the splitting of optical signals of different wavelengths.

[0080] In one possible implementation, the beam splitter module 1 further includes an optical collimation component 1 and an optical collimation component 2, with the beam splitter component positioned between the optical collimation component 1 and the optical collimation component 2. The optical collimation component 1 and the optical collimation component 2 are used to collimate the optical signal. This achieves collimation of the optical path through which the optical signal is transmitted.

[0081] As an example, both optical collimation component 1 and optical collimation component 2 may include fiber optic collimators, or both may include devices that function similarly to fiber optic collimators, without limitation.

[0082] One possible implementation involves a beam splitter module (or beam splitter assembly) used to split optical signals of different wavelengths, including:

[0083] Transmit single-mode optical signal 1 and reflect multimode optical signal 2; or,

[0084] The single-mode optical signal 1 is reflected, and the multimode optical signal 2 is transmitted.

[0085] Specifically, the beam splitter module (or beam splitter component) has different optical functions for light signals of different wavelengths. For example, the beam splitter module (or beam splitter component) transmits single-mode light signal 1 and reflects multimode light signal 2; or, for another example, it reflects single-mode light signal 1 and transmits multimode light signal 2. In this way, a single beam splitter module (or beam splitter component) can complete the beam splitting of light signals of different wavelengths. The beam splitting principle of the beam splitter component is described below with reference to Figures 5 and 6.

[0086] Figure 5 is a schematic diagram of a beam splitting principle. As shown in Figure 5, optical action 1 is reflection, optical action 2 is transmission, and beam splitting module 1 includes: a thin-film filter (an example of a beam splitting component), an optical fiber collimator 1 (an example of an optical collimation component 1), a multimode fiber (an example of port 2), a multiclad fiber (an example of port 3), an optical fiber collimator 2 (an example of an optical collimation component 2), and a single-mode fiber (an example of port 1). Exemplary examples:

[0087] The single-mode fiber outputs a single-mode optical signal 1. The transmission path of the single-mode optical signal 1 (indicated by solid arrows) is: single-mode fiber, fiber collimator 1, thin-film filter (for transmitting the single-mode optical signal 1), fiber collimator 1, and the core of the multi-clad fiber.

[0088] The multi-clad optical fiber receives multimode optical signal 2. The transmission path of multimode optical signal 2 (indicated by dashed arrows) is as follows: the core and cladding of the multi-clad optical fiber, fiber collimator 1, thin-film filter (for transmitting multimode optical signal 2), fiber collimator 2, and multimode optical fiber.

[0089] Figure 6 is another schematic diagram of the beam splitting principle. As shown in Figure 6, optical action 1 is transmission, optical action 2 is reflection, and beam splitting module 1 includes: a thin-film filter (an example of a beam splitting component), an optical fiber collimator 1 (an example of an optical collimation component 1), a multimode fiber (an example of port 2), a multiclad fiber (an example of port 3), an optical fiber collimator 2 (an example of an optical collimation component 2), and a single-mode fiber (an example of port 1). Exemplary examples:

[0090] The single-mode fiber outputs a single-mode optical signal 1. The transmission path of the single-mode optical signal 1 (indicated by the dashed arrow) is: single-mode fiber, fiber collimator 2, thin-film filter (for transmitting the single-mode optical signal 1), fiber collimator 1, and the core of the multi-clad fiber.

[0091] The multi-clad optical fiber receives multimode optical signal 2. The transmission path of multimode optical signal 2 (indicated by solid arrows) is as follows: the core and cladding of the multi-clad optical fiber, fiber collimator 1, thin film filter (to reflect multimode optical signal 2), fiber collimator 1, and multimode optical fiber.

[0092] Based on the content described in Figures 5 and 6, the embodiments of this application can support the implementation of spectral splitting of optical signals of different wavelengths.

[0093] In one possible implementation, the optical device 1 (not limited to the optical device 2) also includes a mode field matcher disposed between the optical antenna module 1 and the beam splitter module 1.

[0094] By setting a mode field matcher between the beam splitter module 1 and the optical antenna module 1, it is beneficial to match the transmitting mode field and the receiving mode field, so that the transmitted beam corresponding to the single-mode optical signal 1 meets the divergence angle and transmitting aperture requirements at the exit pupil (i.e., the emission point) of the optical antenna module 1. At the same time, it can ensure that the received spot of the multimode optical signal 2 does not exceed the core diameter of the multimode optical fiber, thus ensuring high receiving efficiency.

[0095] In this application embodiment, the mode field matcher includes various implementation methods, including but not limited to: optical transformation components, fiber microlenses, and multi-clad fibers based on expanded core fibers. See Figures 7 to 9 for details.

[0096] Figure 7 is a schematic diagram of the deployment of the optical conversion component. As shown in Figure 7, the optical conversion component is located between the beam splitter module 1 and the optical antenna module 1, or in other words, between port 3 and the optical antenna module 1. The optical conversion component is used to control the optical field characteristics of the optical signals transmitted by the optical antenna module 1 (such as the exit pupil of single-mode optical signal 1 and the focal plane of multimode optical signal 2). The optical conversion component includes, but is not limited to: diffusers, diffractive optical elements (DOE) phase plates, gratings, arrayed microlenses, homogenizing fibers, etc.

[0097] By setting up optical transformation components, this can increase the optical spread (a parameter used to describe the geometric characteristics of the beam, defining the product of the beam cross-sectional area and the beam divergence angle), so that the transmitted beam of the single-mode optical signal 1 meets the divergence angle and transmission aperture requirements at the exit pupil (i.e., the transmission point) of the optical antenna module 1. It can also reduce the influence on the light spot of the multimode optical signal 2 passing through the atmospheric turbulence channel, so that the received light spot of the multimode optical signal 2 does not exceed the core diameter of the multimode fiber, ensuring high reception efficiency.

[0098] Figure 8 is a schematic diagram of the deployment of fiber optic microlenses. As shown in Figure 8, the fiber optic microlens is disposed on the fiber end face of port 3, or in other words, the fiber optic microlens is disposed on the fiber end face of a multi-clad fiber. The fiber optic microlens can be an independent microlens, or it can be a spherical fiber optic microlens obtained by sintering the pigtail of a multi-clad fiber, or a tapered fiber optic microlens obtained by grinding; the shape of the microlens is not limited.

[0099] By setting up fiber optic microlenses, for single-mode transmission, the fiber optic microlenses can reduce the divergence angle of single-mode optical signal 1, thereby increasing the focal length of the optical system in the transmission optical path and matching the core size and NA of the multimode fiber; for multimode reception, the fiber optic microlenses can increase the receiving field of view of multimode optical signal 2 (a parameter used to describe the angular range that the optical system can receive, i.e., if the incident angle of multimode optical signal 2 exceeds the receiving field of view of the multimode fiber, it cannot enter the multimode fiber).

[0100] In this embodiment, the fiber optic microlens may include spherical microlenses or conical microlenses, as shown in Figure 9.

[0101] Figure 9 is a schematic diagram of different shapes of fiber optic microlenses. As shown in Figure 9(a), fiber optic microlenses include spherical fiber optic microlenses. As shown in Figure 9(b), fiber optic microlenses include tapered microlenses.

[0102] Figure 10 is a schematic diagram of a multi-clad fiber based on expanded core fiber. As shown in Figure 10, the core diameter of the multi-clad fiber based on expanded core fiber is different in different cross-sections. For example, the core diameter of the multi-clad fiber in cross-section 1 is larger than the diameter in cross-section 2, and cross-section 1 is different from cross-section 2.

[0103] One possible implementation involves thermally expanding the core of a multi-clad fiber to obtain a multi-clad fiber based on the expanded core. This increases the core diameter of the multi-clad fiber, thereby increasing the focal length of the transmitting system of optical device 1 (not limited to optical device 2). Furthermore, since the thermal expansion operation has minimal impact on the cladding of the multi-clad fiber, the focal length of the transmitting system of optical device 1 (not limited to optical device 2) can also match the diameter of the inner cladding of the multi-clad fiber with the NA (na).

[0104] In one possible implementation, optical device 1 (not limited to optical device 2) may also include a single-mode wavelength division multiplexer and a multi-mode wavelength division multiplexer. The single-mode wavelength division multiplexer is disposed between the transmitting module and the beam splitting module (or port 1), and the multi-mode wavelength division multiplexer is disposed between the receiving module and the beam splitting module (or port 2). See Figure 11 for details.

[0105] Figure 11 is a schematic diagram of an optical device. As shown in Figure 11, the optical device 1 includes a transmitting module 1, a single-mode wavelength division multiplexer, a beam splitting module 1, a receiving module 1, a multi-mode wavelength division multiplexer, and an optical antenna module 1. The single-mode wavelength division multiplexer is disposed between the transmitting module 1 and the beam splitting module 1, and the multi-mode wavelength division multiplexer is disposed between the beam splitting module 1 and the receiving module 1.

[0106] By setting up a single-mode wavelength division multiplexer (WDM) between the transmitting module 1 and the beam splitter (or port 1), when the transmitting module 1 outputs multiple single-mode optical signals of different wavelengths, the WDM can combine these multiple single-mode optical signals, thus supporting applications in multi-wavelength scenarios. Similarly, by setting up a multi-mode wavelength division multiplexer (MWD) between the receiving module 1 and the beam splitter (or port 2), when the beam splitter (or port 2) outputs a composite multi-mode optical signal composed of multiple multi-mode optical signals of different wavelengths, the MWD can split this composite multi-mode optical signal, thus supporting applications in multi-wavelength scenarios.

[0107] In one possible implementation, the optical device 1 (not limited to the optical device 2) may also include an optical amplifier disposed between the transmitting module 1 and the beam splitting module 1 (or port 1). This would enable power amplification of the single-mode optical signal 1.

[0108] In one possible implementation, the optical device 1 (not limited to the optical device 2) may also include an optical fiber filter positioned between the beam splitter module 1 (or port 2) and the receiver module 1. This allows for separation between signal transmission and signal reception; that is, the receiver module 1 will not receive the single-mode optical signal 1.

[0109] For a description of the structure of the optical amplifier and fiber optic filter, please refer to Figure 12.

[0110] Figure 12 is a schematic diagram of another structure of the optical device. As shown in Figure 12, the optical device 1 includes a transmitting module 1, an optical amplifier, a beam splitting module 1, a receiving module 1, an optical fiber filter, and an optical antenna module 1. The optical amplifier is located between the transmitting module 1 and the beam splitting module 1 (or port 1), and the optical fiber filter is located between the beam splitting module 1 and the receiving module 1 (or port 2).

[0111] One possible implementation is that the optical devices shown in Figures 3 to 12 can be applied to free-space optical communication scenarios via atmospheric channels. Specifically, atmospheric channels refer to communication channels through which lasers transmit information in the atmospheric medium, including communication between satellites and ground stations, communication between ground stations, and communication between aerial drones / hot air balloons, etc. When the aforementioned optical devices are applied to free-space optical communication scenarios via atmospheric channels, this can improve the stability of the transceiver coaxiality of the optical devices in atmospheric channel application scenarios.

[0112] In this embodiment, in addition to the components shown in Figures 3 to 12, the optical device 1 may also include an auxiliary light source and an optical system for aiming, capturing, and tracking. Specific connection relationships are not limited.

[0113] In summary, those skilled in the art will recognize that the units of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0114] In the embodiments provided in this application, it should be understood that the disclosed electronic devices and apparatuses can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between devices or modules, and may be electrical, mechanical, or other forms.

[0115] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed in multiple places. Some or all of the modules can be selected to achieve the purpose of the embodiments of this application, depending on actual needs.

[0116] In addition, the functional modules in the embodiments of this application can be integrated into one unit, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0117] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An optical device, characterized in that, include: Transmitting module, receiving module, beam splitting module, and optical antenna module; The beam splitter is connected to the transmitting module, the receiving module, and the optical antenna module, respectively. The beam splitting module is used for: Based on the function of splitting optical signals of different wavelengths, the single-mode optical signal output by the transmitting module is output to the optical antenna module, and the multimode optical signal received by the optical antenna module is output to the receiving module, wherein the wavelength of the single-mode optical signal is different from the wavelength of the multimode optical signal; The optical antenna module is used to transmit the single-mode optical signal and receive the multimode optical signal, and the receiving module is used to process the multimode optical signal.

2. The optical device according to claim 1, characterized in that, The beam splitter module is connected to the transmitting module via a single-mode optical fiber, the beam splitter module is connected to the receiving module via a multi-mode optical fiber, and the beam splitter module is connected to the optical antenna module via a multi-clad optical fiber.

3. The optical device according to claim 1 or 2, characterized in that, The optical device further includes a mode field matcher, which is disposed between the optical antenna module and the beam splitter module.

4. The optical device according to claim 3, characterized in that, The mode field matcher includes an optical transformation component, which is used to control the optical field characteristics of the optical signal transmitted by the optical antenna module.

5. The optical device according to claim 3, characterized in that, The mode field matcher includes an optical fiber microlens disposed on the end face of a multi-clad optical fiber, and the beam splitter is connected to the optical antenna module through the multi-clad optical fiber.

6. The optical device according to claim 3, characterized in that, The mode field matcher includes a multi-clad fiber based on expanded core fiber, and the beam splitter is connected to the optical antenna module through the multi-clad fiber based on expanded core fiber.

7. The optical device according to any one of claims 1 to 6, characterized in that, The beam splitter module includes at least one of the following: Thin-film filters, fused biconical taper fiber, or fiber Bragg gratings.

8. The optical device according to any one of claims 1 to 7, characterized in that, The beam splitting function for optical signals of different wavelengths includes: The single-mode optical signal is transmitted, and the multimode optical signal is reflected; or, The single-mode optical signal is reflected, and the multimode optical signal is transmitted.

9. The optical device according to any one of claims 1 to 8, characterized in that, The optical device further includes a single-mode wavelength division multiplexer and a multi-mode wavelength division multiplexer. The single-mode wavelength division multiplexer is disposed between the transmitting module and the beam splitting module, and the multi-mode wavelength division multiplexer is disposed between the receiving module and the beam splitting module.

10. The optical device according to any one of claims 1 to 9, characterized in that, The optical device further includes an optical fiber filter, which is disposed between the receiving module and the beam splitting module.

11. The optical device according to any one of claims 1 to 10, characterized in that, The optical device further includes an optical amplifier, which is disposed between the transmitting module and the beam splitting module.

12. The optical device according to any one of claims 1 to 11, characterized in that, The optical device is used in free-space optical communication scenarios that pass through atmospheric channels.

13. A free-space optical communication system, characterized in that, The free-space optical communication system includes a first optical device, which includes the optical device according to any one of claims 1 to 13; The first optical device is used to transmit a first single-mode optical signal to the second optical device and receive a second multimode optical signal. The second multimode optical signal is an optical signal obtained based on the second single-mode optical signal transmitted by the second optical device. The wavelength of the first single-mode optical signal is different from the wavelength of the second single-mode optical signal.

14. The free-space optical communication system according to claim 13, characterized in that, The free-space optical communication system further includes the second optical device, which includes the optical device according to any one of claims 1 to 13; The second optical device is used to transmit the second single-mode optical signal to the first optical device and to receive the first multimode optical signal, wherein the first multimode optical signal is an optical signal obtained based on the first single-mode optical signal.

Images