An optical wireless beam alignment method using a multi-core fiber

Abstract

An OWC subsystem (400) to establish bidirectional optical data communication with a remote OWC subsystem comprises: a bundle of optical fiber cores (405) arranged in a predetermined shape; an optical transceiver (401) to transmit and receive data light beams via a first optical fiber core; an auxiliary beacon transmitter (402); at least two auxiliary beacon receivers (403), each to receive a respective beacon light beam from the remote OWC subsystem via a respective optical fiber core; a fiber splitter (404) to split a beacon light beam from the auxiliary beacon transmitter (402) into at least two transmitted beacon light beams and to provide each of these transmitted beacon light beams to a respective optical fiber core; and a collimator (407) to focus data and / or beacon light beams from the remote OWC subsystem to a common end facet (406) of the bundle (405) and to collimate data and / or transmitted beacon light beams from the common end facet (406).

Description

Technical Field

[0001] This invention relates to the field of optical wireless communication, such as Li-Fi communication. More particularly, this document discloses various devices, systems, and methods related to secure optical wireless communication systems. Background Technology

[0002] To enable an increasing number of electronic devices, such as laptops, tablets, and smartphones, to wirelessly connect to the internet, wireless communication faces unprecedented demands for data rates and link quality, and these demands are growing year by year, especially considering the emerging digital revolution associated with the Internet of Things (IoT). Radio frequency (RF) technologies like Wi-Fi, with their limited spectrum capacity, are ill-suited to meet this revolution. Meanwhile, Light Fidelity (Li-Fi) is attracting growing attention due to its inherent enhanced security and ability to support higher data rates across the available bandwidth of the visible, ultraviolet (UV), and infrared (IR) spectra. Furthermore, compared to Wi-Fi, Li-Fi is directional and shielded by light-blocking materials, making it possible to deploy a greater number of access points in densely populated areas by spatially reusing the same bandwidth. These key advantages make Li-Fi a promising security solution compared to wireless RF communications, alleviating the strain on congested radio spectrum from IoT applications and indoor wireless access. Other potential benefits of Li-Fi include guaranteed bandwidth for a single user and the ability to operate safely in areas otherwise susceptible to electromagnetic interference. Therefore, Li-Fi is a highly promising technology that enables next-generation immersive connectivity.

[0003] To achieve high data throughput in short-range point-to-point optical links, a narrow-beam transmitter source and a small, low-capacitance optical receiver are used. Due to this narrow-beam characteristic, precise alignment between the transmitter and receiver is essential. For non-static systems, this can be achieved using different types of electromechanical actuators and beam-tracking methods.

[0004] A low-cost and compact method for beam tracking can be implemented using an additional low-frequency beacon transmitter. The system works well when the distance between the optical transmitter and receiver is long. For short distances, however, due to the near-field transmission characteristics, deviations in tracking can be significant because the high-speed optical transceiver is physically separated from the low-frequency beacon-based tracking system. To address this, the unit can be calibrated to compensate for deviations at a specific communication distance *d*. However, calibration is only effective for systems operating at a fixed communication distance, not for fully dynamic systems.

[0005] US2020366371A1 relates to systems and methods for providing high-throughput connections between multiple network nodes, such as satellites or ground stations in Earth orbit, using a multiplexed free-space optical communication transceiver. The transceiver includes a focal plane array having an array of movable optical fibers or fiber bundles, multi-core optical fibers, or combinations thereof. Each fiber bundle may include a central data fiber with guide fibers arranged around it.

[0006] US5777768A relates to a method for establishing a laser link communication system in free space, the system comprising first and second terminals located far apart from each other on an optical path. Each terminal includes multiple laser emitters that together generate multiple laser beams, each laser beam carrying a communication signal.

[0007] US2022107473A1 relates to a free-space optical communication device comprising an optical fiber bundle and one or more processors. The optical fiber bundle includes a central optical fiber connected to a first photodetector and a plurality of surrounding optical fibers, each surrounding optical fiber being connected to a corresponding second photodetector. Summary of the Invention

[0008] The present invention aims to address the problem of reducing the arrangement constraints of discrete data and beacon / pilot transceivers (or transmitters / receivers) in high-speed narrow-beam optical communication (sub) systems, wherein the transceivers include associated optics for beam alignment and acquisition, pointing and tracking, while enhancing the compactness of the high-speed narrow-beam optical communication (sub) system.

[0009] In view of the above, the present invention relates to the OWC system as claimed in claim 13, the method as claimed in claim 14, and the optical wireless communication OWC subsystem as claimed in claim 1.

[0010] According to a first aspect of the present invention, an OWC subsystem is provided. The OWC subsystem is configured to establish bidirectional optical data communication with a remote OWC subsystem for point-to-point narrow-beam optical wireless communication, comprising: - Fiber core bundle, including the common end face facing the collimator; - An optical transceiver is configured to transmit and receive corresponding transmit and receive data beams to and from a remote OWC subsystem via the first fiber core of the bundle; - An auxiliary beacon transmitter is configured to provide a beacon beam to the fiber optic splitter; - At least two auxiliary beacon receivers, each of which is configured to receive the corresponding beacon beam from the remote OWC subsystem via the corresponding fiber core of the bundle; - An optical fiber splitter, directly coupled to at least an auxiliary beacon transmitter, and configured to split a beacon beam from the auxiliary beacon transmitter into at least two transmit beacon beams, each transmit beacon beam having the same amount of output power, and to supply each of the at least two transmit beacon beams to a corresponding fiber core of the bundle; and The collimator is configured to focus data and / or beacon beams received from the remote OWC subsystem onto a common end face, and to collimate data and / or at least two transmitted beacon beams from the common end face for transmission to the remote OWC subsystem. The fiber cores of this bundle are arranged in a predetermined shape, and The beacon beam is used for bidirectional beam alignment between the OWC subsystem and the remote OWC subsystem, such that the alignment of the OWC subsystem (400) with the remote OWC subsystem is achieved when the corresponding amount of optical power received in each fiber core carrying the beacon beam from the remote OWC subsystem is determined to be equal.

[0011] Therefore, instead of using a specific arrangement of discrete beacon / pilot beam transmitters and receivers, including associated optics, such as symmetrically positioned around the aperture of the data beam from the discrete optical transceivers, fiber core bundles are used, where the different cores of the bundle serve different purposes in the alignment process based on beacon / pilot and data transmission, as well as reception / detection. Thus, by transferring these arrangement constraints to the fiber core bundles that subsequently need to be arranged in a predetermined shape, the arrangement constraints of these discrete components can be avoided in the context of the alignment process. Consequently, easier electromagnetic compatibility (EMC) shielding and better utilization of existing space can be achieved due to the inherent flexibility of the fiber cores.

[0012] Advantageously, the predetermined shape of the fiber core arrangement can be defined by different arrangements of the fiber cores carrying the transmit beacon beam and the fiber cores carrying the beacon beam from the remote OWC subsystem, respectively, around the first fiber core carrying the corresponding transmit and receive data beams. Therefore, the arrangement constraints can be applied to the fiber cores, and not to the discrete auxiliary beacon transmitter / receiver and the discrete optical transceiver.

[0013] Advantageously, different arrangements can include symmetrical arrangements and / or arrangements based on the circle-within-a-circle problem. Thus, the fiber cores carrying the transmitting beacon beam and the fiber cores carrying the beacon beam from the remote OWC subsystem can be arranged symmetrically around a first fiber core, and / or the fiber cores carrying the transmitting beacon beam and the fiber cores carrying the beacon beam from the remote OWC subsystem can be arranged based on the circle-within-a-circle problem to enhance compactness. Note that although two-dimensional circular packing is aimed at packing a unit circle into a larger circle that is as small as possible, the fiber cores of the bundle (corresponding to the larger circle, with the smaller circle packed within the larger circle) can have any diameter, whether the diameter is the same or different.

[0014] Preferably, the symmetrical arrangement can define at least one of the following arrangements: a circular data beam and an elliptical beacon beam arrangement, an elliptical data beam and a circular beacon beam arrangement, and a circular data beam and a circular beacon beam arrangement on the common end core face.

[0015] Advantageously, the first fiber core carrying the corresponding transmitted and received data beams can be placed at the center of the bundle. Therefore, the position of the first fiber core on the common end face facing the collimator can be predetermined so that the collimator can be advantageously used to mitigate any data beam divergence.

[0016] Advantageously, the first fiber core on the common end face can be placed at the focal point of the collimator. Therefore, the lowest possible data beam divergence can be achieved.

[0017] Preferably, the fiber core bundle may include an optical multi-core fiber or a bundle of multiple optical single-core fibers.

[0018] Preferably, the collimator may include imaging optics, non-imaging optics, or a combination thereof. For example, the collimator may include a conventional lens or optical system, such as an air-spaced doublet or a coaxial optics device.

[0019] Preferably, each of the at least two auxiliary beacon receivers may include at least one of a photodiode, a camera sensor (e.g., a CMOS or InGaAs image sensor), an endoscope sensor, a silicon photomultiplier tube (SiPM), and a single-photon avalanche diode (SPAD). Note that a photodiode may also refer to a photodetector, photodetector, or photosensor, which may be a PIN diode, an avalanche photodiode (APD), or a photomultiplier tube, and the SiPM array may be a parallel SPAD array.

[0020] Preferably, the fiber cores carrying the beacon beam from the remote OWC subsystem can be coupled to at least two auxiliary beacon receivers. Therefore, two options are possible. In the first option, when the number of fiber cores carrying the beacon beam from the remote OWC subsystem is equal to the number of these auxiliary beacon receivers, the coupling can be performed "directly," i.e., without through a fiber optic splitter. In the first option, each fiber core carrying the beacon beam from the remote OWC subsystem is directly coupled to the corresponding auxiliary beacon receiver (i.e., with a 1:1 coupling ratio). In the second option, when the number of fiber cores carrying the beacon beam from the remote OWC subsystem is different from the number of these auxiliary beacon receivers, the coupling can be performed "indirectly," i.e., through a fiber optic splitter. In the second option, splitting is then required, and the fiber optic splitter can be directly coupled to the auxiliary beacon receivers.

[0021] Advantageously, the OWC subsystem may include an actuator system configured to manipulate the transmitted data beam and / or the transmitted beacon beam. Manipulation can be achieved using a fast steering mirror (FSM), a voice coil mirror, a prism, etc.

[0022] Advantageously, the optical transceiver and at least three of the at least two auxiliary beacon receivers can be further configured to detect the incident angle of the corresponding data and beacon beam from the remote OWC subsystem, at least based on a predetermined shape of the fiber cores arranged at the common end face. Thus, in the example case of three auxiliary beacon receivers, the corresponding three fiber cores carrying their respective beacon beams from the remote OWC subsystem can be spaced apart at a 120-degree angle at the common end face. In the example case where the possibility of detecting the incident angle is combined with the use of a fast-direction system for manipulating the data and beacon beam received from the remote OWC, the corresponding redirection algorithm does not need to determine the beam position based on the maximum received optical power. Instead, it directly manipulates the direction of the received beam and is therefore able to respond more quickly when detecting and tracking the beam.

[0023] Advantageously, alignment between the OWC subsystem and the remote OWC subsystem can be achieved when the corresponding amount of optical power received in each fiber core carrying the beacon beam from the remote OWC subsystem is determined to be equal.

[0024] According to a second aspect of the present invention, an OWC system is provided. The OWC system includes: An OWC subsystem according to the first aspect or any combination thereof, configured to establish bidirectional optical data communication with a remote OWC subsystem for bidirectional beam alignment; and Remote OWC subsystem The OWC subsystem and the remote OWC subsystem are configured to include all other components of each other.

[0025] Therefore, it is advantageous that the OWC system and the remote OWC system are identical to allow the beam alignment process to be performed from both sides.

[0026] According to a third aspect of the invention, a method is provided performed at an OWC subsystem for establishing bidirectional optical data communication with a remote OWC subsystem for point-to-point narrow-beam optical wireless communication, wherein the OWC subsystem includes an optical transceiver, at least two auxiliary beacon receivers, an auxiliary beacon transmitter, an optical fiber splitter directly coupled to at least the auxiliary beacon transmitter, an optical fiber core bundle including a common end face facing a collimator, and a collimator. The method includes: - The optical transceiver transmits and receives corresponding transmit and receive data beams to and from the remote OWC subsystem via the first fiber core of the bundle; - The auxiliary beacon transmitter provides the beacon beam to the fiber optic splitter; - The corresponding beacon beams are received from the remote OWC subsystem by two auxiliary beacon receivers via the corresponding fiber cores of the bundle; - The beacon beam from the auxiliary beacon transmitter is split into at least two transmit beacon beams by an optical fiber splitter, each transmit beacon beam having the same amount of output power; - A fiber optic splitter supplies each of at least two transmitting beacon beams to the corresponding fiber core of the bundle; and - The collimator focuses the data and / or beacon beams received from the remote OWC subsystem onto the common end face, and the collimator also collimates the data and / or at least two transmitted beacon beams from the common end face for transmission to the remote OWC subsystem. The fiber cores of this bundle are arranged in a predetermined shape, and The beacon beam is used for bidirectional beam alignment between the OWC subsystem and the remote OWC subsystem, such that the alignment of the OWC subsystem (400) with the remote OWC subsystem is achieved when the corresponding amount of optical power received in each fiber core carrying the beacon beam from the remote OWC subsystem is determined to be equal. Attached Figure Description

[0027] In the accompanying drawings, similar reference numerals often refer to the same parts throughout the different figures. Furthermore, the drawings are not necessarily drawn to scale; instead, the emphasis is usually on illustrating the principles of the invention.

[0028] Figure 1 An example of a beam alignment setup according to the prior art is shown; Figure 2 An example of a control loop in a device according to the prior art is shown; Figure 3 An example of a schematic free-space optical communication system according to the prior art is shown; Figure 4 An example of an OWC subsystem according to the present invention is shown; Figure 5 Examples of different fiber core arrangements in the common end face are shown according to the present invention; Figure 6 An example is shown according to the present invention when a light spot is received on a common end face; Figure 7 An example flowchart of a method performed at the OWC subsystem according to the present invention is shown. Detailed Implementation

[0029] The embodiments described below represent information that enables those skilled in the art to practice these embodiments. Upon reading the following description in conjunction with the accompanying drawings, those skilled in the art will understand the concepts of this disclosure and will recognize the application of these concepts, which are not specifically set forth herein. It should be understood that these concepts and applications fall within the scope of this disclosure.

[0030] To achieve high data throughput in short-range point-to-point optical wireless communication, narrow-beam transmitter sources and small, low-capacitance (optical) receivers are typically used. Due to this narrow-beam characteristic, precise alignment between the transmitter and receiver is essential. For non-static systems, this requires different types of electromechanical actuators and beam-tracking methods.

[0031] Figure 1 An example of a beam alignment setup according to the prior art is shown. As shown, the point-to-point narrow beam OWC system 100 includes two (first and second) identical OWC units 101, 102 placed facing each other. For clarity, only the main components 103-107 of the first optical wireless unit 101 are shown, and the facing second OWC unit 102 correspondingly includes the same main components 103-107. A high-speed optical wireless transceiver 107, including a narrow beam transmitter and a receiver, is placed at the center of the plate or surface of the first OWC unit 101. Two auxiliary beacon transmitters 105 and 106, configured to transmit low-frequency beacon signals with the same output power, are placed next to the optical transceiver 107 at a distance of b = b'. Two auxiliary four-quadrant (optical) receivers 103 and 104, configured to detect beacons from the facing OWC unit 102 for beam alignment, are placed next to the optical transceiver 107 at a distance of a = a'. Mechanical actuator ( Figure 1 Each complete OWC unit 101, 102 (not shown in the figure) will be moved independently on the x (roll)-y (pitch) axis to align the optical transceiver 107 with the matched optical transceiver 107 of the facing optical wireless communication unit 102 based on the received signals tracked in the two auxiliary quadrant (optical) receivers 103, 104 from the facing OWC unit 102.

[0032] like Figure 2 As shown, an example implementation of the control loop 200 in OWC units 101, 102 according to the prior art is illustrated, in which signals received in the respective quadrants of the two auxiliary quadrant (optical) receivers 103, 104 are summed. This, together with the use of two auxiliary beacon transmitters in the facing OWC unit 102 to generate the same beacon, will compensate for the tracking deviation caused by the physical separation between the auxiliary beacon transmitter / auxiliary quadrant (optical) receiver and the high-speed optical transceiver.

[0033] The sum of signals from the two four-quadrant (optical) receivers 103 and 104 generates four signals, which are fed to an analog-to-digital converter (ADC) in the controller 201 of the OWC unit 101. The controller 201 processes these signals to generate an error vector and, together with the mechanical actuator 202, creates closed-loop control. When the error falls below a certain threshold or approaches zero and has a predetermined tolerance, the actuator stops, resulting in the alignment of the two OWC units 101 and 102.

[0034] Regarding this point-to-point narrow beam OWC system 100, the solution of the present invention can provide the following advantages: - Improve compactness by using existing and required collimators to focus and collimate the data and beacon beams together; - Eliminate the limitations of placing discrete beacon transmitters / receivers and optical transceivers in a particular arrangement, such as placing discrete beacon transmitters and receivers symmetrically around discrete optical transceivers, thereby allowing for easier EMC shielding and better utilization of existing space due to the flexibility of optical fibers. - Use smaller optical and electromechanical devices to steer the combined beacon and data beams, since these combined beams are collimated together by a collimator; - Avoid using expensive beam splitters and other optical components used to combine or separate beacon and data beams; - Avoid using internal optical feedback mechanisms in the auxiliary beacon transmitter of each unit to compensate for optical power differences caused by LED / laser binning and aging, as an LED can be used by connecting two fiber cores or a fiber splitter; - The characteristics (differences, beam shape) of data and beacon beams are manipulated by selecting a dedicated arrangement of fiber cores on the end facets located in the region surrounding the collimator focus.

[0035] Figure 3An example of an illustrative free-space optical (FSO) communication system 300 according to the prior art is shown. This illustrative FSO communication system 300 is derived from a telescope control system, as shown in Qing Li et al., “An improved method for the position detection of a quadrant detector for free space optical communication”, Sensors 2019 (online published by MDPI), 19(1), 175, https: / / doi.org / 10.3390 / s19010175. An FSO communication system 300, provided in each optical communication terminal (OCT), includes a telescope 301, a fast-straightening mirror (FSM) 302 for combining beams from the telescope 301, a beam splitter 303 with a semi-reflecting mirror for splitting the combined beam into reflected beacon beams as beacon light independently received by each quadrant of a four-quadrant detector (QD) 304 and transmitted data beams received by a data receiver 305, and an FSM control loop including an amplifier 306, an analog-to-digital converter 307, a position calculation module 308, a controller 309, and an FSM driver 310 for driving the FSM 302. The amplifier 306 amplifies the corresponding photocurrent output from each quadrant of the QD 304, and the amplitude of the photocurrent corresponds to the energy of the beacon light illuminating each quadrant respectively. The position calculation module 308 estimates the beacon light based on the ratio of the photocurrent amplitudes.

[0036] Regarding the FSO communication system 300 using conventional beam splitters and (semi)mirrors, the solution of the present invention can offer the following benefits: - Avoid using beam splitters, thereby avoiding the need for additional absorbing materials required to absorb optical power in specific branches and sections, and minimizing any misunderstandings by the beacon / pilot receiver.

[0037] Figure 4 An example of an OWC subsystem 400 according to the present invention is shown. In this setup, the OWC subsystem 400 is oriented towards a remote, identical OWC subsystem ( Figure 4(Not shown) is placed for establishing bidirectional optical data communication. The main components of the OWC subsystem 400 include: an optical fiber core bundle 405, including a common end face 406 facing the collimator 407; an optical transceiver 401 configured to transmit and receive corresponding transmit and receive data beams to and from the remote OWC subsystem via the first optical fiber core of the bundle 405; an auxiliary beacon transmitter 402 configured to provide a beacon beam to the optical fiber splitter 404; and at least two auxiliary beacon receivers 403, each configured to receive a corresponding beacon beam from the remote OWC subsystem via the corresponding optical fiber core of the bundle 405. The bundle 405 comprises: an optical fiber splitter 404 directly coupled to at least an auxiliary beacon transmitter 402 and configured to split a beacon beam from the auxiliary beacon transmitter 402 into at least two transmit beacon beams, and to provide each of the at least two transmit beacon beams to a corresponding optical fiber core of the bundle 405; and a collimator 407 configured to focus data and / or beacon beams received from the remote OWC subsystem onto a common end face 406, and to collimate data and / or at least two transmit beacon beams from the common end face 406 for transmission to the remote OWC subsystem. The optical fiber cores of the bundle 405 are arranged in a predetermined shape, and the beacon beams are used for bidirectional beam alignment between the OWC subsystem 400 and the remote OWC subsystem.

[0038] Optical transceiver 401 may be an optical wireless high-speed transceiver for high-speed data communication, which may preferably include a narrow-beam light source for data beam transmission. The light source may be one of a light-emitting diode (LED), a laser diode, a vertical-cavity surface-emitting laser (VCSEL), or an edge-emitting laser diode (EELD). Preferably, optical transceiver 401 may include at least one of an LED and a VCSEL, and auxiliary beacon transmitter 402 may include an LED. Auxiliary beacon transmitter 402 and each auxiliary beacon receiver 403 may be a respective narrow-beam transmitter and receiver, which use beacon / pilot light transmission and reception for beam alignment and acquisition, pointing, and tracking. Beam angle or beam width is the aperture angle that radiates most of the power. For example, half-power beam width is the angle between the half-power (-3dB) points of the main lobe of the radiation pattern. For a horizontal plane, beam angle or beam width is typically expressed in degrees. A beam angle of 10 degrees or less is generally considered narrow.

[0039] In cases where it is necessary to split the transmit data beam into at least two transmit data beams and provide each of them to the corresponding first fiber core of the bundle 405, the fiber optic splitter 404 can be directly coupled to the optical transceiver 401.

[0040] In one example, fiber optic splitter 404 can be directly coupled to at least two auxiliary beacon receivers 403, provided that the number of fiber cores carrying the beacon beam from the remote OWC subsystem is different from the number of the at least two auxiliary beacon receivers 403. Therefore, fiber cores carrying the beacon beam from the remote OWC subsystem are "indirectly" coupled to at least two auxiliary beacon receivers, i.e., by passing through fiber optic splitter 404.

[0041] In an alternative example, fiber optic splitter 404 may not be coupled to at least two auxiliary beacon receivers 403, provided that the number of fiber cores carrying the beacon beam from the remote OWC subsystem is equal to the number of at least two auxiliary beacon receivers 403. Thus, each fiber core carrying the beacon beam from the remote OWC subsystem is "directly" coupled to the corresponding auxiliary beacon receiver 403 (i.e., with a 1:1 coupling ratio), that is, without through fiber optic splitter 404. To illustrate such an alternative example, Figure 4 The bottom outline of the fiber optic splitter 404 facing the auxiliary beacon receiver 403 is shown in dashed lines.

[0042] The fiber core bundle 405 may include optical multi-core fibers or multiple optical single-core fiber bundles.

[0043] Collimator 407 may include imaging optics or non-imaging optics, or a combination thereof. For example, collimator 407 may include a common lens or optical system, such as an air-spaced doublet or a coaxial optics device.

[0044] Figure 5 Examples of different fiber core arrangements 500A, 500B, and 500C at a common end face 406 according to the present invention are shown. As shown, each fiber core is associated with a dedicated function of transmission (TX) and / or reception (RX) of data and beacon beams. Fiber core arrangements 500A, 500B, and 500C are symmetrical and include a circular data beam and elliptical beacon beam arrangement 500A, an elliptical data beam and circular beacon beam arrangement 500B, and a circular data beam and circular beacon beam arrangement 500C. Those skilled in the art will understand that other types of fiber core arrangements at end face 406 are also possible. For example, the fiber core arrangement can be based on the well-known problem of filling a circle within a circle, which involves filling a unit circle into a larger circle that is as small as possible. In the present invention, the fiber cores can correspond to the smaller circle, the bundle 405 can correspond to the larger circle, wherein the smaller circle is filled, and the fiber cores can have any diameter of the same or different dimensions.

[0045] Figure 6An example of the case where a light spot is received at a common end face 406 according to the present invention is shown. In this example, the fiber core TX carrying the transmit beacon beam (beacon TX) from the opposing remote OWC subsystem and the fiber cores RX1, RX2, RX3 carrying the beacon beams (beacon RX1 to beacon RX3) are arranged around the first fiber core TRX carrying the corresponding transmit and receive data beams (data TRX), thus defining a symmetrical fiber core arrangement. As shown by the gray dashed circle, the light spot emitted from the auxiliary beacon transmitter 402 at the remote OWC subsystem is received at the location corresponding to the focal point of the collimator 407. Each fiber core carrying the beacon beams (beacon RX1 to beacon RX3) is assumed to be directly coupled to the corresponding auxiliary beacon receiver 403, such as a corresponding photodiode, for detecting the optical power emitted by the light spot. Figure 6 As shown, the light spot is not perfectly centered relative to the first fiber core located at the center of bundle 405, therefore the optical power received at fiber cores RX1, RX2, and RX3 is not equal. Figure 6 In the example, the OWC subsystem 400 and the remote OWC subsystem are not (perfectly) aligned due to the received optical power difference. Note that the auxiliary beacon receiver 403 (e.g., a photodiode) can also use the received optical power difference to determine a rough value of the angle of incidence of the beam received from the remote OWC subsystem.

[0046] Figure 7 An example flowchart of a method 700 for establishing bidirectional optical data communication with a remote OWC subsystem, performed at an OWC subsystem 400 according to the present invention, is shown. The OWC subsystem 400 includes an optical transceiver 401, an auxiliary beacon transmitter 402, at least two auxiliary beacon receivers 403, an optical fiber splitter 404 directly coupled to at least the auxiliary beacon transmitter 402, an optical fiber core bundle 405 including a common end face 406 facing a collimator 407, and a collimator 407. Method 700 includes the following steps: In step S701, the optical transceiver 401 transmits a data beam to the remote OWC subsystem via the first fiber core of the bundle 405, and in step S701', the optical transceiver 401 receives a data beam from the remote OWC subsystem via the first fiber core of the bundle 405. In step S702, the two auxiliary beacon receivers 403 receive the corresponding beacon beams from the remote OWC subsystem via the corresponding fiber cores of bundle 405; In step S703, the auxiliary beacon transmitter 402 provides a beacon beam to the fiber optic splitter 404; In step S704, the beacon beam from the auxiliary beacon transmitter 402 is split into at least two transmitting beacon beams by the fiber optic splitter 404; In step S705, the fiber optic splitter 404 supplies each of at least two transmitting beacon beams to the corresponding fiber core of the bundle 405; and In step S706, the collimator 407 focuses the data and / or beacon beams received from the remote OWC subsystem onto the common end face 406, and in step S706', the collimator 407 collimates the data and / or at least two transmitted beacon beams from the common end face 406 for transmission to the remote OWC subsystem. The fiber cores of the 405 bundle are arranged in a predetermined shape, and The beacon beam is used for bidirectional beam alignment between OWC subsystem 400 and the remote OWC subsystem.

[0047] The method 700 according to the present invention can be implemented on a computer as a computer-implemented method, or in dedicated hardware, or in a combination of both.

[0048] The executable code of the method 700 according to the present invention can be stored on a computer / machine-readable storage device. Examples of computer / machine-readable storage devices include non-volatile storage devices, optical storage media / devices, solid-state media, integrated circuits, servers, etc. Preferably, the computer program product includes non-transitory program code means stored on a computer-readable medium for executing the method 700 according to the present invention when the program product is executed on a computer.

[0049] Methods, systems, and computer-readable media (temporary and non-temporary) may also be provided to implement selected aspects of the above embodiments.

Claims

1. An optical wireless communication OWC subsystem (400) configured to establish bidirectional optical data communication with a remote OWC subsystem for point-to-point narrow-beam optical wireless communication, the OWC subsystem (400) comprising: The fiber core bundle (405) includes a common end core face (406) facing the collimator (407); An optical transceiver (401) is configured to transmit to and receive corresponding transmit and receive data beams from the remote OWC subsystem via the first fiber core of the bundle (405); An auxiliary beacon transmitter (402) is configured to provide a beacon beam to the fiber optic splitter (404); At least two auxiliary beacon receivers (403), each of which is configured to receive a corresponding beacon beam from the remote OWC subsystem via a corresponding fiber core of the bundle (405); An optical fiber splitter (404) is directly coupled to at least an auxiliary beacon transmitter (402) and is configured to split a beacon beam from the auxiliary beacon transmitter (402) into at least two transmitting beacon beams, each transmitting beacon beam having the same amount of output power, and to provide each of the at least two transmitting beacon beams to a corresponding optical fiber core of a bundle (405). and A collimator (407) is configured to focus data and / or beacon beams received from a remote OWC subsystem onto a common end facet (406), and to collimate data and / or at least two transmitted beacon beams from the common end facet (406) for transmission to the remote OWC subsystem. The fiber cores of the bundle (405) are arranged in a predetermined shape, and The beacon beam is used for bidirectional beam alignment between the OWC subsystem (400) and the remote OWC subsystem, such that alignment between the OWC subsystem (400) and the remote OWC subsystem is achieved when the corresponding amount of optical power received in each fiber core carrying the beacon beam from the remote OWC subsystem is determined to be equal.

2. The OWC subsystem according to claim 1, wherein, The predetermined shape of the fiber core arrangement is defined by different arrangements of the fiber core carrying the transmit beacon beam and the fiber core carrying the beacon beam from the remote OWC subsystem, respectively, around the first fiber core carrying the corresponding transmit and receive data beams.

3. The OWC subsystem according to claim 2, wherein, The different arrangements include symmetrical arrangements and / or arrangements based on the problem of circles within circles.

4. The OWC subsystem (400) according to claim 3, wherein, The symmetrical arrangement defines at least one of the following at the common end core face (406): a circular data beam and an elliptical beacon beam arrangement (500A), an elliptical data beam and a circular beacon beam arrangement (500B), and a circular data beam and a circular beacon beam arrangement (500C).

5. The OWC subsystem (400) according to any one of the preceding claims, wherein, The first fiber core carrying the corresponding transmit and receive data beam is located at the center of the bundle (405).

6. The OWC subsystem (400) according to any one of the preceding claims, wherein, The first fiber core at the common end core face (406) is located at the focal point of the collimator (407).

7. The OWC subsystem (400) according to any one of the preceding claims, wherein, The fiber core bundle (405) includes an optical multi-core fiber or a bundle of multiple optical single-core fibers.

8. The OWC subsystem (400) according to any one of the preceding claims, wherein, The collimator (405) includes an imaging optical portion or a non-imaging optical portion or a combination thereof.

9. The OWC subsystem (400) according to any one of the preceding claims, wherein, Each of the at least two auxiliary beacon receivers (403) includes at least one of a photodiode, a camera sensor, an endoscope sensor, a silicon photomultiplier tube, and a single-photon avalanche diode.

10. The OWC subsystem (400) according to claim 9, wherein, The fiber core carrying the beacon beam from the remote OWC subsystem is coupled to at least two auxiliary beacon receivers (403).

11. The OWC subsystem (400) according to any one of the preceding claims further includes an actuator system configured to manipulate the transmission data beam and / or the transmission beacon beam.

12. The OWC subsystem (400) according to any one of the preceding claims, wherein, At least three of the optical transceiver (401) and the at least two auxiliary beacon receivers (403) are also configured to detect corresponding data from the remote OWC subsystem and the incident angle of the beacon beam, based at least on a predetermined shape of the fiber core arranged at the common end face (406).

13. An OWC system, comprising: The OWC subsystem (400) according to any one of the preceding claims is configured to establish bidirectional optical data communication with a remote OWC subsystem for bidirectional beam alignment; and Remote OWC subsystem The OWC subsystem (400) and the remote OWC subsystem are configured to include all other components of each other.

14. A method (700) performed at an OWC subsystem (400) for establishing bidirectional optical data communication with a remote OWC subsystem for point-to-point narrow-beam optical wireless communication, the OWC subsystem (400) including an optical transceiver (401), an auxiliary beacon transmitter (402), at least two auxiliary beacon receivers (403), an optical fiber splitter (404) directly coupled to at least the auxiliary beacon transmitter (402), an optical fiber core bundle (405) including a common end face (406) facing a collimator (407), and a collimator (407), the method (700) comprising: The optical transceiver (401) transmits (S701) and receives (S701') corresponding transmit and receive data beams from the remote OWC subsystem via the first fiber core of the bundle (405); The auxiliary beacon transmitter (402) provides (S702) the beacon beam to the fiber optic splitter (404); The corresponding beacon beams from the remote OWC subsystem are received (S703) by two auxiliary beacon receivers (403) via the corresponding fiber cores of the bundle (405); The beacon beam from the auxiliary beacon transmitter (402) is split (S704) into at least two transmitting beacon beams by an optical fiber splitter (404), each transmitting beacon beam having the same amount of output power; The fiber optic splitter (404) provides (S705) each of the at least two transmitting beacon beams to the corresponding fiber core of the bundle (405); and The collimator (407) focuses (S706) the data and / or beacon beams received from the remote OWC subsystem onto the common end face (406), and the collimator (407) collimates (S706') the data and / or at least two transmitted beacon beams from the common end face (406) for transmission to the remote OWC subsystem. The fiber cores of the bundle (405) are arranged in a predetermined shape, and The beacon beam is used for bidirectional beam alignment between the OWC subsystem (400) and the remote OWC subsystem, such that alignment between the OWC subsystem (400) and the remote OWC subsystem is achieved when the corresponding amount of optical power received in each fiber core carrying the beacon beam from the remote OWC subsystem is determined to be equal.

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