Optical spatial communication devices, mobile devices, base stations, and communication systems

Abstract

To provide a spatial optical communication device that transmits and receives a large amount of information in a short period of time with high confidentiality at a transmission speed of gigabit per second or more between a large number of moving devices or between a fixed device and a moving device.SOLUTION: A spatial optical communication device transmits a transmission optical signal to a communication target, receives a reception optical signal from the communication target, and communicates with the communication target. The spatial optical communication device includes a transmitter that changes the direction of a beam of the transmission optical signal toward the communication target and transmits the transmission optical signal to the communication target, and a receiver that receives the reception optical signal from the communication target.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to spatial optical communication devices, mobile devices, base stations, and communication systems. [Background technology]

[0002] Patent Documents 1 and 2 each disclose a spatial optical communication device connecting a ground station and an artificial satellite. The distance between the transceiver in the spatial optical communication devices disclosed in Patent Documents 1 and 2 ranges from tens of kilometers to tens of thousands of kilometers. The spatial optical communication devices disclosed in Patent Documents 1 and 2 each consist of a large telescope optical system.

[0003] Furthermore, Patent Documents 3 and 4 each disclose numerous robot control methods using wireless communication.

[0004] Furthermore, Patent Documents 5 and 6 each disclose a method for determining location by projecting light over a wide area. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6920710 [Patent Document 2] Japanese Patent Publication No. 2021-027437 [Patent Document 3] Patent No. 4505998 [Patent Document 4] Japanese Patent Application Publication No. 05-233059 [Patent Document 5] International Publication No. 2017 / 169911 [Patent Document 6] Japanese Patent Publication No. 2009-055408 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The spatial optical communication devices disclosed in Patent Documents 1 and 2 are composed of large telescope optical systems, making them difficult to mount on devices moving on the Earth or water, devices flying through the atmosphere, or devices moving underwater. Furthermore, the artificial satellites used in the spatial optical communication devices disclosed in Patent Documents 1 and 2 have orbital information, making it possible to estimate their position. However, the position of a general mobile device must be obtained by a different method. In addition, neither Patent Document 1 nor Patent Document 2 discloses a lightweight mechanism capable of rapidly tracking a communication partner for spatial optical communication.

[0007] Furthermore, in the wireless communication methods for controlling multiple robots disclosed in Patent Documents 3 and 4, the communication speed is at most a few hundred megabits per second due to the low frequency of the carrier wave. Also, wireless communication is difficult in environments with poor electromagnetic fields or underwater, and operating multiple devices simultaneously can cause interference, resulting in communication failure or reduced communication speed. Moreover, wireless communication is easily intercepted, making highly confidential communication difficult. Furthermore, in wireless communication, the usable frequency bands are restricted by legal regulations, except for very weak radio waves.

[0008] Furthermore, neither Patent Document 5 nor Patent Document 6 discloses a method for estimating the orientation of the device.

[0009] In light of the circumstances described above, this disclosure provides a spatial optical communication device that transmits and receives large amounts of information in a short time with high confidentiality at a transmission speed of gigabits per second or more between a number of moving devices or between a fixed device and a moving device. [Means for solving the problem]

[0010] In one aspect of the present disclosure, there is provided a free-space optical communication device that transmits a transmitted optical signal to a communication target, receives a received optical signal from the communication target, and communicates with the communication target. The free-space optical communication device includes a transmitter that changes the direction of an optical beam of the transmitted optical signal toward the communication target and transmits the transmitted optical signal to the communication target, and a receiver that receives the received optical signal from the communication target.

Advantages of the Invention

[0011] According to the free-space optical communication device of the present disclosure, a large amount of information can be transmitted and received at a transmission rate of gigabits per second or more between a plurality of moving bodies or between a fixed base station and a moving body in a short time with high confidentiality.

Brief Description of the Drawings

[0012] [Figure 1] FIG. 1 is a diagram for explaining the usage state of the free-space optical communication device according to the first embodiment. [Figure 2] FIG. 2 is a diagram for explaining the outline of the transmitter in the free-space optical communication device according to the first embodiment. [Figure 3] FIG. 3 is a diagram for explaining the configuration of the transmitter in the free-space optical communication device according to the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining the configuration of the transmitter in the free-space optical communication device according to the first embodiment. [Figure 5] FIG. 5 is a diagram for explaining the outline of the receiver in the free-space optical communication device according to the first embodiment. [Figure 6] FIG. 6 is a diagram for explaining the configuration of the receiver in the free-space optical communication device according to the first embodiment. [Figure 7] FIG. 7 is a diagram for explaining the configuration of the receiver in the free-space optical communication device according to the first embodiment. [Figure 8] FIG. 8 is a diagram for explaining the optical systems of the transmitter and the receiver in the free-space optical communication device according to the first embodiment. [Figure 9] FIG. 9 is a diagram for explaining the outline of the transmitter in the free-space optical communication device according to the second embodiment. [Figure 10] Figure 10 is a schematic diagram illustrating the transmitter in the spatial optical communication device according to the second embodiment. [Figure 11] Figure 11 illustrates the optical beam transmitted from the transmitter in the spatial optical communication device according to the second embodiment. [Figure 12] Figure 12 is a schematic diagram illustrating the transmitter in the spatial optical communication device according to the third embodiment. [Figure 13] Figure 13 is a schematic diagram illustrating the transmitter in a spatial optical communication device according to the third embodiment. [Figure 14] Figure 14 illustrates the optical beam transmitted from the transmitter in the spatial optical communication device according to the third embodiment. [Figure 15] Figure 15 illustrates a mobile body in which the spatial optical communication device according to the fourth embodiment is used. [Figure 16] Figure 16 illustrates a mobile body in which the spatial optical communication device according to the fourth embodiment is used. [Figure 17] Figure 17 illustrates the optical beacon section in a mobile device using the spatial optical communication device according to the fourth embodiment. [Figure 18] Figure 18 illustrates a mobile device and a base station in which the spatial optical communication device according to the fifth embodiment is used. [Modes for carrying out the invention]

[0013] The embodiments will be described below with reference to the attached drawings. However, this disclosure is not limited to these examples, and all modifications are intended to be included in the meaning and scope equivalent to the claims, as indicated by the claims.

[0014] In addition, regarding the descriptions and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be denoted by the same reference numerals, thereby omitting redundant explanations. Furthermore, for ease of understanding, the scale of each part in the drawings may differ from that of the actual parts.

[0015] A degree of deviation is permissible in directions such as parallel, right angles, orthogonal, horizontal, vertical, up and down, left and right, and front and back, as long as it does not impair the effectiveness of the embodiment. The shape of the corners is not limited to right angles and may be rounded in an arc shape. Parallel, right angles, orthogonal, horizontal, and vertical may include approximately parallel, approximately right angles, approximately orthogonal, approximately horizontal, and approximately vertical, respectively.

[0016] For example, "approximately parallel" means that two lines or two planes can be treated as parallel to each other within a manufacturingly acceptable range, even if they are not perfectly parallel. Similarly, "approximately right angle," "approximately perpendicular," "approximately horizontal," and "approximately vertical" are intended to apply as long as the relative positions of the two lines or two planes are within a manufacturingly acceptable range.

[0017] ≪First Embodiment≫ <Structure> First, a spatial optical communication device according to the first embodiment will be described. Figure 1 is a diagram illustrating the state in which the spatial optical communication device 10 according to the first embodiment is used. In Figure 1, the spatial optical communication device 10A will be used as an example of a communication target with which the spatial optical communication device 10 communicates. The spatial optical communication device 10A is a spatial optical communication device with the same configuration as the spatial optical communication device 10. The spatial optical communication device 10 communicates with the spatial optical communication device 10A using an optical burst signal.

[0018] The spatial optical communication device 10 comprises a transmitter 11, a receiver 12, and a control unit 13. The spatial optical communication device 10A, which is the communication target of the spatial optical communication device 10, also comprises a transmitter 11, a receiver 12, and a control unit 13, similar to the spatial optical communication device 10. The spatial optical communication device 10 transmits an optical burst signal from the transmitter 11 to the spatial optical communication device 10A. The spatial optical communication device 10 also receives the optical burst signal transmitted from the spatial optical communication device 10A via the receiver 12.

[0019] [Transmitter 11] The transmitter 11 transmits a transmission optical signal Lt to the spatial optical communication device 10A, which is the communication target. The transmitter 11 can change the direction of the light rays of the transmission optical signal Lt toward the spatial optical communication device 10A, which is the communication target.

[0020] Figure 2 is a conceptual diagram showing the configuration of the transmitter 11 in the spatial optical communication device 10 according to the first embodiment. The transmitter 11 comprises a light source unit 11a and an optical beam control unit 11b.

[0021] The light source unit 11a is, for example, a semiconductor laser that is directly modulated. However, the light source unit 11a is not limited to a semiconductor laser that is directly modulated; for example, it may also consist of a semiconductor laser and an optical modulator, and the continuous light emitted from the semiconductor laser may be modulated by the optical modulator.

[0022] The optical beam control unit 11b controls the beam diameter (radius ω0) and emission direction of the optical beam of the transmitted optical signal Lt transmitted from the transmitter 11. The beam diameter of the optical beam of the transmitted optical signal Lt can be freely changed, for example, using a lens or mirror. The emission direction of the optical beam of the transmitted optical signal Lt is controlled by providing a mechanism that rotates around the X axis and Y axis in the coordinate system shown in Figure 2.

[0023] Figure 3 illustrates a mechanism for rotating the emission direction of the light beam of the transmitted optical signal Lt around the X and Y axes. For example, as a two-axis rotation mechanism, the eyeball-shaped drive mechanism 11c is used for robots. As a mechanism for rotating the emission direction of the light beam of the transmitted optical signal Lt in the optical beam control unit 11b, one possible method is to position the end face of an optical fiber or the end face of a collimator lens at the rotation center of the eyeball portion of the drive mechanism 11c.

[0024] Figure 4 illustrates a mechanism for rotating the emission direction of the light beam of the transmitted optical signal Lt around the X-axis and Y-axis. The drive mechanism 11c comprises an optical fiber 11d and a beam diameter adjustment lens 11e.

[0025] The optical fiber 11d transmits the transmitted optical signal Lt output from the light source unit 11a to the drive mechanism 11c. At the end of the optical fiber 11d in the drive mechanism 11c, a TEC (Thermally-Expanded-Core) structure is provided in the optical fiber or an optical collimating lens is added to increase the mode field diameter at the optical fiber end.

[0026] The end of the beam diameter adjustment lens 11e, in other words, the point of light emission in the beam diameter adjustment lens 11e, is positioned at the rotation center 11ca of the drive mechanism 11c. By positioning the end of the beam diameter adjustment lens 11e at the rotation center 11ca of the drive mechanism 11c, and by rotating the eyeball portion of the drive mechanism 11c, the emission direction of the transmitted optical signal Lt can be controlled around the X and Y axes.

[0027] The drive mechanism 11c rotates the emission direction of the light beam of the transmitted optical signal Lt around the X axis and Y axis, for example, based on a control signal from the control unit 13. The control unit 13 controls the emission direction of the light beam of the transmitted optical signal Lt based on the position and orientation of the communication target, etc.

[0028] [Receiver 12] The receiver 12 receives the received optical signal Lr from the spatial optical communication device 10A, which is the communication target.

[0029] Figure 5 is a conceptual diagram showing the configuration of the receiver 12 in the spatial optical communication device 10 according to the first embodiment. The receiver 12 comprises a lens 12a, a photodiode 12b, and a receiving circuit 12c.

[0030] Lens 12a focuses the received optical signal Lr onto photodiode 12b. Lens 12a is a lens with radius r and focal length f.

[0031] The photodiode 12b converts the received optical signal Lr into an electrical signal. The photodiode 12b is connected to the receiving circuit 12c. The photodiode 12b is installed at a distance d from the lens 12a.

[0032] The receiving circuit 12c drives the photodiode 12b and receives the electrical signal converted by the photodiode 12b. The electrical signal received by the receiving circuit 12c is transmitted, for example, to the control unit 13.

[0033] Assume that the spatial optical communication device 10 and the spatial optical communication device 10A, which is the communication target, are separated by a distance L. Distance L is longer than radius r. Because distance L is longer than radius r, the incident light entering the receiver 12 can be approximated as a plane wave. The received optical signal Lr incident on lens 12a is focused at a focal length f from lens 12a, since the received optical signal Lr can be considered a plane wave. Therefore, the installation distance d is equal to the focal length f of lens 12a.

[0034] On the other hand, if the incident beam of the received optical signal Lr is incident from a direction shifted by an angle θ with respect to the Z axis, the focal point will be moved away from the Z axis by a distance fθ. If the shift in the focal point becomes greater than the diameter of the photodiode 12b, the photodiode 12b will not be able to receive the received optical signal Lr.

[0035] Figure 6 illustrates an example in which a photodiode array 12d is used instead of a photodiode 12b. The photodiode array 12d comprises multiple light-receiving elements (photodiodes 12da). By using the photodiode array 12d instead of a photodiode 12b, the received light signal Lr can be received even when the received light signal Lr is incident at an oblique angle to the optical axis of the lens 12a of the receiver 12. The photodiode array 12d comprises, for example, a photodiode 12da having a square light-receiving surface with sides of length s. The photodiodes 12da are arranged in the X-axis direction and the Y-axis direction with intervals s.

[0036] As shown in Figure 7, the receiver 12 may also be equipped with an optical axis rotation mechanism 12e similar to that of the transmitter 11. In other words, the receiver 12 may be equipped with a direction control unit that controls the receiving direction.

[0037] [Control Unit 13] The control unit 13 controls the transmitter 11 and the receiver 12. The control unit 13 controls the intensity (modulation control) and direction of the transmitted optical signal Lt transmitted from the transmitter 11 based on the transmitted data. The control unit 13 also converts the received optical signal Lr received by the receiver 12 from an electrical signal into received data.

[0038] <Optical System Design> Next, we will explain the design of the optical system. Here, we will explain the design of the optical system using Figure 8. We will explain with spatial optical communication device 10 as the transmitting side and spatial optical communication device 10A as the receiving side.

[0039] Let L be the distance between the spatial optical communication device 10 and the spatial optical communication device 10A. Let ω1 be the beam diameter at the receiving spatial optical communication device 10A of the transmitted optical signal Lt transmitted from the transmitter 11 of the spatial optical communication device 10. Furthermore, let δL be the distance from the optical axis Lt1 of the transmitted optical signal Lt to the receiver 12 of the spatial optical communication device 10A, and let θ0 be the angle of incidence of the transmitted optical signal Lt to the receiver 12.

[0040] If the lens of receiver 12 (the lens corresponding to lens 12a of receiver 12) is within the light beam of the transmitted optical signal Lt, the power of the light beam is P out Therefore, the light receiving power P in This is approximated by Equation 1.

[0041]

number

[0042] For example, initially, δL=0, v is the relative velocity of the transmitted optical signal Lt in the direction perpendicular to the optical axis Lt1, and t is the duration of the burst light of the transmitted optical signal Lt. b If that is the case, then we need to ignore the lens diameter and satisfy the inequality in Equation 2.

[0043]

number

[0044] Furthermore, the minimum receiving sensitivity of receiver 12 is set to P r Therefore, it is clear that equation 3 holds true.

[0045]

number

[0046] We will consider this using specific numerical values. Although it depends on the size of the spatial optical communication device 10 and the spatial optical communication device 10A, we would like to avoid mounting a large optical system, so the radius r of the lens 12a will be set to 2 centimeters (cm). The wavelength of the transmitted optical signal Lt will be set to 1500 nanometers (nm). Also, the transmission power of the transmitted optical signal Lt from the transmitter 11, i.e., P out 10 is a typical value. -2 Let's assume the value is in watts (W). If the bitrate of the optical signal is 10 gigabits per second (Gbps), then the minimum receiving sensitivity P is... r As a typical value, 10 -4It is watts (W). From Equation 3, it can be seen that ω1 needs to be 20 centimeters (cm) or less.

[0047] Also, for example, if the relative speed between the free-space optical communication device 10 and the free-space optical communication device 10A is 100 meters per second (m / s), from Equation 2, the time length t of the burst light b should be sufficiently shorter than 2×10 -3 seconds. Further, if the relative speed between the free-space optical communication device 10 and the free-space optical communication device 10A is 0.1 meters per second (m / s), from Equation 2, the time length t of the burst light b should be sufficiently shorter than 2 seconds.

[0048] On the other hand, time is required for synchronization in burst signal reception. The time for synchronization in burst signal reception is 10 -8 seconds in the case of a high-performance receiver. Therefore, in the communication between the free-space optical communication device 10 and the free-space optical communication device 10A, when the relative speed is 100 meters per second (m / s), the duration of the burst light is about 10 -7 seconds to 10 -4 seconds. Also, when the moving speed is 0.1 meters per second (m / s), it is about 10 -7 seconds to 10 -1 seconds.

[0049] For example, if the duration of the burst signal is 10 -5 seconds, 100,000 bits of information can be transmitted in one burst. In order to receive a 10 gigabits per second (Gbps) signal, the photodiode needs to operate at high speed and is required to be small. In the receiver 12, as shown in FIG. 5, the length s of one side of the photodiode 12b is 0.1 millimeter (mm). For example, as shown in FIG. 6, when a photodiode array is used, if the photodiode array has a photodiode in an N×N array, when N is 8, the light receiving diameter is 0.8 millimeter (mm). It is necessary to satisfy Equation 4 for the incident light to be condensed on the photodiode.

[0050]

number

[0051] For example, when the focal length f of lens 12a is 10 centimeters (cm), θ0 is 8 × 10 -3 The value must be less than or equal to radians (rad). Therefore, as shown in Figure 7, it may be equipped with an optical axis rotation mechanism 12e similar to that of the transmitter 11.

[0052] ≪Second Embodiment≫ Next, a spatial optical communication device according to the second embodiment will be described. Figures 9 and 10 show schematic diagrams of the transmitter 111 of the spatial optical communication device according to the second embodiment. Figure 9 is a view of the transmitter 111 from the +Y side along the Y-axis direction opposite to the Y-axis. Figure 10 is a view of the transmitter 111 from the -X side along the X-axis direction. The spatial optical communication device according to the second embodiment is equipped with a transmitter 111 in place of the transmitter 11 of the spatial optical communication device 10 according to the first embodiment.

[0053] The transmitter 111 comprises a plurality of transmitting units 111a and a lens 111b. The transmitting units 111a are light beam generating units. That is, the transmitter 111 comprises a plurality of light beam generating units. Each of the plurality of transmitting units 111a comprises a semiconductor laser 111c and a silicon substrate 111d. The semiconductor laser 111c generates a transmitted optical signal Lt. The silicon substrate 111d has an input optical waveguide 111e which is a silicon optical waveguide, a pair of n optical switches 111f, and a plurality of output optical waveguides 111g which are silicon optical waveguides. The transmitted optical signal Lt is input to the input optical waveguide 111e. The output ends 111h of each of the plurality of output optical waveguides 111g are located within the focal plane of the lens 111b. By positioning the output ends 111h of each of the multiple output optical waveguides 111g within the focal plane of the lens 111b, the emitted light is geometrically converted into parallel light by the lens 111b.

[0054] Furthermore, the output ends 111h of each of the multiple output optical waveguides 111g are located at different positions from one another. Because the output ends 111h of each of the multiple output optical waveguides 111g are located at different positions from one another, the light emitted from each output end 111h of each of the multiple output optical waveguides 111g is emitted in different directions depending on the output end 111h. The optical switch 111f is used to select one of the multiple output optical waveguides 111g. By selecting one of the multiple output optical waveguides 111g using the optical switch 111f, the direction of emission of the optical beam can be controlled.

[0055] Let's examine the configuration using specific numerical values, as shown in Figure 11. Generally, the beam diameter (radius, ω) of the light emitted from a silicon optical waveguide is enlarged to increase the spot size. s The distance d between the waveguide and the optical axis is 2 micrometers (μm). s Let this be 0.5 millimeters (mm). The focal length of lens 111b is f s Let this be 5 centimeters (cm). Here, let the distance l1 from the waveguide end to 123 be 5.22 centimeters (cm). Approximating the light beam with a Gaussian beam, the lens 111b gives the beam waist diameter ω out This is 45 micrometers (μm). Also, the beam angle θ s This can be expressed by equation 5 using the geometrical optics approximation. Using equation 5, the beam diameter ω s This is approximately 0.01 radians (rad).

[0056]

number

[0057] At a point 20 meters (m) away from transmitter 111, the beam diameter (radius) is approximately 20 centimeters (cm). Also, the angle θ sCorrespondingly, it shifts 20 centimeters (cm) from the optical axis. In other words, by setting the waveguide end spacing to 0.5 millimeters (mm) and switching the waveguide from which the beam is emitted, a beam with a diameter of 20 centimeters (cm) can be moved and scanned in 20-centimeter (cm) increments at a point 20 meters (m) away.

[0058] As shown in Figures 8 and 9, by stacking multiple transmitting units 111a, the beam can be scanned in the Y-axis direction as well. The operating speed of the silicon waveguide optical switch, which utilizes the thermo-optic effect, is fast, at approximately 30 microseconds (μs).

[0059] The semiconductor laser 111c is an example of a photogenerating unit, and the silicon substrate 111d is an example of a photoswitching unit.

[0060] ≪Third Embodiment≫ Next, a spatial optical communication device according to the third embodiment will be described. Figures 12 and 13 show schematic diagrams of the transmitter 211 of the spatial optical communication device according to the third embodiment. Figure 12 is a view of the transmitter 211 from the +Y side along the Y-axis direction opposite to the Y-axis. Figure 13 is a view of the transmitter 211 from the -X side along the X-axis direction. The spatial optical communication device according to the third embodiment includes a transmitter 211 in place of the transmitter 11 of the spatial optical communication device 10 according to the first embodiment. The transmitter 211 acts as an optical beam diameter changing unit.

[0061] The transmitter 211 comprises a transmitting unit 211a and a plurality of lenses 211b. The transmitting unit 211a comprises a semiconductor laser 211c and a silicon substrate 211d. The semiconductor laser 211c generates a transmit optical signal Lt. The silicon substrate 211d has an input optical waveguide 211e, which is a silicon optical waveguide, a pair of n optical switches 211f, and a plurality of output optical waveguides 211g, which are silicon optical waveguides. The transmit optical signal Lt is input to the input optical waveguide 211e. The output ends 211h of each of the plurality of output optical waveguides 211g are positioned opposite the corresponding lenses 211b.

[0062] Each of the multiple lenses 211b has a different focal length. Because the focal lengths and distances to the waveguide ends of each of the multiple lenses 211b are different, each of the multiple lenses 211b emits a beam with a different diameter depending on the output end. By selecting one of the multiple output optical waveguides 211g using the optical switch 211f, the beam diameter of the optical beam can be controlled.

[0063] Let's examine the configuration using specific numerical values, as shown in Figure 14. Generally, the beam diameter (radius, ω) of the light emitted from a quartz optical waveguide. s The diameter is 5 micrometers (μm). Here, we consider lens 211b with focal lengths of 1, 2 and 3 centimeters (cm).

[0064] For example, consider lens 211b with a focal length of 1 centimeter (cm). Let's assume the distance to the waveguide end is 1.25 centimeters (cm). That is, the focal length of lens 211b is 1 centimeter (cm), and the distance to the waveguide end is 1.25 centimeters (cm). In this case, the beam waist diameter is 20 micrometers (μm), and the beam diameter at a distance of 20 meters (m) is 50 centimeters (cm).

[0065] For example, consider lens 211b with a focal length of 2 centimeters (cm). Let's assume the distance to the waveguide end is 2.25 centimeters (cm). That is, the focal length of lens 211b is 2 centimeters (cm), and the distance to the waveguide end is 2.25 centimeters (cm). In this case, the beam waist diameter is 40 micrometers (μm), and the beam diameter at a distance of 20 meters (m) is 25 centimeters (cm).

[0066] For example, consider lens 211b with a focal length of 3 centimeters (cm). Let's assume the distance to the waveguide end is 3.25 centimeters (cm). That is, the focal length of lens 211b is 3 centimeters (cm), and the distance to the waveguide end is 3.25 centimeters (cm). In this case, the beam waist diameter is 60 micrometers (μm), and the beam diameter at a distance of 20 meters (m) is 16 centimeters (cm).

[0067] As described above, the range illuminated by the transmitted optical signal Lt can be controlled by switching the optical switch 211f. For example, if the lens diameter is 1.5 centimeters (cm) and the distance between the waveguide ends is 1.5 centimeters (cm), optical beams from adjacent waveguides will not enter adjacent lenses, nor will the lenses overlap. In other words, the beam divergence angle can be changed by selecting the emitting waveguide. The optical beam position shifts in the X-axis direction, but the effect is minimal at the receiving end, where the beam diameter expands to more than 15 centimeters (cm) at a distance of 20 meters (m). The operation speed of the quartz waveguide optical switch, which utilizes the thermo-optic effect, is relatively fast, at about 2 milliseconds (ms).

[0068] The semiconductor laser 211c is an example of a photogenerating unit, and the silicon substrate 211d is an example of a photoswitching unit.

[0069] ≪Fourth Embodiment≫ Next, we will describe the situations in which the spatial optical communication device according to this embodiment is used. Figure 15 is a diagram illustrating a mobile body 500 using the spatial optical communication device according to this embodiment.

[0070] <Structure> The mobile unit 500 is a device having a movement mechanism. The mobile unit 500 is a mobile device. Examples of the mobile unit 500 include a bipedal robot, a car with wheels or caterpillar tracks, a drone or aircraft with a flight device, a ship or submarine with a propeller or water jet, etc.

[0071] Communication using optical burst signals is performed between the mobile units 500 using the spatial optical communication device according to this embodiment.

[0072] Figure 16 is a diagram illustrating the details of the mobile unit 500. The mobile unit 500 comprises a spatial optical communication device 10, a wireless communication unit 510, an optical beacon unit 520, an imaging unit 530, a distance measuring unit 540, a mobile mechanism unit 550, and a central control unit 560.

[0073] The wireless communication unit 510 communicates with other mobile devices 500 using radio waves. The wireless communication unit 510 includes an antenna 511 and a wireless control circuit 512.

[0074] The optical beacon unit 520 is a so-called optical beacon transceiver. The optical beacon unit 520 transmits optical signals in all directions. The optical beacon unit 520 also receives optical signals from all directions. The optical beacon unit 520 comprises a transceiver unit 521 and an optical beacon control circuit 522.

[0075] Figure 17 is a diagram illustrating the overview of the transmitting / receiving unit 521 of the optical beacon unit 520. The transmitting / receiving unit 521 comprises an optical receiving unit 523 and an optical transmitting unit 524.

[0076] The light receiving unit 523 has multiple photodiodes 525 mounted in different orientations so that it can receive light from all directions.

[0077] The optical transmitting unit 524 is composed of multiple light sources 526. The multiple light sources 526 in the optical transmitting unit 524 are visible from the outside. For example, the optical transmitting unit 524 has the light sources 526 arranged at the vertices of a tetrahedron. For example, the imaging unit 530 of another mobile body 500 can image the light sources 526, and the attitude of the mobile body 500 can be estimated from the two-dimensional arrangement of the image captured by the imaging unit 530.

[0078] Furthermore, since the multiple light sources 526 in the optical transmission unit 524 are bright, the speed can be easily estimated from the captured image. Also, by modulating the light sources 526 at a low speed of several megabits per second (Mbps) and receiving it with the optical beacon unit 520 of another mobile device 500, information can be transmitted. By utilizing the optical beacon unit 520, low-speed optical communication is possible even in poor electromagnetic environments.

[0079] The imaging unit 530 images the area around the moving object 500. The imaging unit 530 includes an optical system 531 and an image processing circuit 532. The optical system 531 includes, for example, optical lenses such as zoom lenses, a lens barrel that holds the lenses, and a drive device that changes the orientation of the lenses. The image processing circuit 532 includes an image sensor and stores the results of imaging by the image sensor as an image.

[0080] The distance measuring unit 540 measures the distance to an object around the moving body 500. The distance measuring unit 540 is, for example, a LiDAR (Light Detection and Ranging) system. The distance measuring unit 540 comprises an optical system 541 and a distance processing circuit 542.

[0081] The moving mechanism 550 generates a driving force to move the moving body 500. The moving body 500 includes, for example, a motor.

[0082] The central control unit 560 controls the entire mobile unit 500.

[0083] <Processing> This section describes the communication procedure between multiple mobile units 500. Here, we will explain the case where mobile unit 500a and mobile unit 500b communicate as shown in Figure 15. Let's assume that mobile unit 500a needs to communicate with mobile unit 500b.

[0084] (Step S10) Mobile unit 500a transmits a communication request to mobile unit 500b using the wireless communication unit 510. The communication request includes location information, movement information, and attitude information of mobile unit 500a. Mobile unit 500b may receive the request directly, or it may receive it via a network where mobile units 500a and 500b are terminals. Alternatively, mobile unit 500a may transmit an optical signal from its optical beacon unit 520 and have it received by the optical beacon unit 520 of mobile unit 500b, without using the wireless communication unit 510.

[0085] (Step S20) If mobile body 500b permits the request, it transmits a permit signal to mobile body 500a using the wireless communication unit 510. Simultaneously, it transmits the mobile body 500b's location information, movement information, attitude information, etc. In addition, an optical beacon is emitted from the optical beacon unit 520, a low-speed signal is superimposed, and the latest location information, movement information, and individual identification information, etc. are transmitted. The permit signal and location information, etc. may also be transmitted and received using the optical beacon unit 520. Furthermore, since the optical beacon unit 520 is equipped with multiple light sources 526, the attitude of mobile body 500b and the distance to mobile body 500b may be estimated from the arrangement of light sources when imaged by the imaging unit 530.

[0086] (Step S30) Next, the mobile unit 500b performs optical signal reception preparation processing. The mobile unit 500b obtains the position information and movement information of the mobile unit 500a from the radio wave signal received by the wireless communication unit 510, the image signal obtained from the imaging unit 530, the signal superimposed on the optical beacon obtained by the optical beacon unit 520, and the signal obtained from the distance measurement unit 540. Then, the mobile unit 500b performs attitude control so that the optical axis of the transmitter 11 is in the direction of the mobile unit 500a. It is also possible to superimpose information onto the transmission signal from the optical beacon unit 520 of the mobile unit 500b and receive it with the optical beacon unit 520 of the mobile unit 500a. The optical beacon unit 520 emits an optical beacon toward the mobile unit 500a. A low-speed signal is superimposed on the optical beacon, and the latest position information, movement information, and individual identification information are transmitted.

[0087] (Step S40) Mobile unit 500a also performs attitude control in the same way as mobile unit 500b.

[0088] (Step S50) Once attitude control is complete, the transmitter 11 and receiver 12 exchange information by transmitting and receiving optical burst signals to each other. Their respective position information, movement information, and attitude information are constantly updated to ensure that the optical axes of the transmitter 11 and receiver 12 align.

[0089] In the above explanation, it was stated that light with a wavelength of 1500 nanometers (nm) would be used because the eye safety restrictions are lax. However, in water, visible light in the wavelength range of 450 to 600 nanometers, which has high transmittance, may also be used. Furthermore, each of the multiple mobile bodies 500 may use a light beam of a different wavelength. By placing a wavelength filter in front of the receiver 12 to allow reception of only specific wavelengths, the transmitting mobile body 500 can be selected.

[0090] Alternatively, step S55 may be performed instead of step S50.

[0091] (Step S55) Once attitude control is complete, the transmitter 11 of mobile body 500a transmits the same optical burst signal while scanning around the assumed position of mobile body 500b. The transmitter 11 of mobile body 500b transmits the same optical burst signal while scanning around the assumed position of mobile body 500a. Since the distance traveled by mobile body 500a and mobile body 500b during the duration of the optical burst signal is small compared to the change in scanning position, either optical burst signal can be received if both mobile body 500a and mobile body 500b are within the scanning range. By scanning the transmitted optical signal Lt, the accuracy of attitude control or transmission direction control can be relaxed.

[0092] ≪Fifth Embodiment≫ Next, we will describe the situations in which the spatial optical communication device according to this embodiment is used. Figure 18 is a diagram illustrating a mobile body 500 using the spatial optical communication device according to this embodiment. Here, communication is also performed between the mobile body 500 and a fixed base station 600 that does not have a mobile mechanism. The mobile body 500 and the base station 600 together are referred to as the communication system 700.

[0093] Since the base station 600 does not have a mobile mechanism, it can be easily enlarged. The base station 600 is equipped with multiple spatial optical communication devices 10, multiple optical beacon units 520, multiple imaging units 530, and multiple distance measuring units 540, and can communicate with multiple mobile units 500 simultaneously.

[0094] When communicating with the base station 600, the mobile unit 500 may be miniaturized by omitting the transmitter 11 or by using simpler equipment for other devices. For example, the base station 600 and multiple mobile units 500 may be operated in master-slave mode.

[0095] The transmitted optical signals Lt from multiple mobile units 500 may utilize optical beams of different wavelengths. The multiple receivers 12 of the base station 600 may each utilize optical beams of different wavelengths. By placing a wavelength filter in front of the receiver 12 to allow reception of only specific wavelengths, the transmitting mobile unit 500 can be selected.

[0096] <Mechanism of action, effect> The spatial optical communication device of this disclosure enables the transmission and reception of large amounts of information in a short time with high security at a transmission speed of gigabits per second or more, between multiple moving devices or between a stationary device and a moving device. The spatial optical communication device of this disclosure allows for the miniaturization of optical transceivers. Furthermore, the spatial optical communication device of this disclosure enables easy tracking of the communication target. Moreover, the spatial optical communication device of this disclosure enables communication even in adverse electromagnetic environments or underwater.

[0097] The spatial optical communication device of this disclosure can provide communication using visible light or near-infrared light between mobile units 500 or between a mobile unit 500 and a fixed base station 600. By performing communication using light, communication is possible even in electromagnetic environments where wireless communication using electromagnetic waves in the range of several megahertz to several gigahertz is difficult.

[0098] Furthermore, by combining an optical beacon, a low-speed optical communication device capable of transmitting and receiving optical signals in all directions, with a high-speed optical burst communication device that utilizes an optical beam directed in a specific direction, high-speed and high-capacity optical communication can be achieved while maintaining attitude control.

[0099] The attitude of the moving object 500 can be estimated by imaging the optical beacon unit 520, which consists of multiple light sources 526. Furthermore, the optical beacon unit 520 facilitates attitude control and optical beam projection direction control for establishing a link. Because it utilizes a directional optical beam, it offers very high security. Long-distance communication underwater is also possible by using a wavelength range of 450 to 600 nanometers. Additionally, different wavelengths of optical beams can be used for each device to avoid interference.

[0100] By positioning the optical fiber end on an eyeball-shaped two-axis rotating mechanism, compact and high-speed optical communication is possible. Furthermore, by controlling the direction of the optical beam using an optical waveguide and optical switches, direction control can be achieved in a time of approximately 30 microseconds.

[0101] Furthermore, by controlling the optical beam diameter using an optical waveguide and optical switch, directional control can be achieved in approximately 2 milliseconds using a quartz optical waveguide. This is difficult with conventional mechanical optical beam control.

[0102] Furthermore, by utilizing optical burst signals, tracking is not required during the duration of the optical burst, enabling communication even between devices moving at high speeds. Additionally, the use of optical burst signals can relax the precision requirements for attitude and direction control.

[0103] Although the spatial optical communication device has been described above with reference to embodiments, the present invention is not limited to the above embodiments. Various modifications and improvements, such as combinations or substitutions with some or all of other embodiments, are possible within the scope of the present invention. [Explanation of symbols]

[0104] 10, 10A Space Optical Communication Device 11, 111, 211 Transmitters 12 Receiver 13 Control Unit 111 Transmitter 111a Transmitter 111b lens 111c semiconductor laser 111d silicon substrate 111e Input optical waveguide 111f Optical switch 111g output optical waveguide 111h Output end 211 Transmitter 211a Transmitter 211b lens 211c semiconductor laser 211d silicon substrate 211e Input optical waveguide 211f Optical Switch 211g output optical waveguide 211h Output end 500, 500a, 500b Mobile Units 510 Wireless Communication Section 520 Optical Beacon Section 530 Imaging Unit 550 Moving mechanism section 560 Central Control Unit 600 base stations 700 Communication Systems

Claims

1. A spatial optical communication device that transmits a transmission optical signal to a communication target, receives a reception optical signal from the communication target, and communicates with the communication target, A transmitter that changes the direction of the light rays of the transmitted optical signal toward the communication target and transmits the transmitted optical signal to the communication target, A receiver that receives the received optical signal from the communication target, Equipped with, The transmitter includes an optical beam diameter changing unit that changes the beam diameter of the transmitted optical signal, The aforementioned optical beam diameter changing unit is A light generation unit that generates the aforementioned transmitted optical signal, An optical switching unit having an input optical waveguide into which the transmitted optical signal is input from the optical generation unit, a plurality of output optical waveguides, and an optical switch that switches and connects the input optical waveguide and the plurality of output optical waveguides, A plurality of lenses are provided outside the aforementioned output optical waveguide, each of which is input to the plurality of output optical waveguides, and which have different focal lengths from each other. Equipped with, The optical switch switches the beam diameter of the transmitted optical signal by switching the output optical waveguide connected to the input optical waveguide. Spatial optical communication device.

2. The receiver comprises a plurality of light-receiving elements. The spatial optical communication device according to claim 1.

3. The receiver includes a direction control unit for controlling the direction of reception. The spatial optical communication device according to claim 1.

4. The transmitter comprises a plurality of light beam generating units. The spatial optical communication device according to claim 1.

5. The transmitted optical signal has a duration of 10 －７ From 10 seconds －１ It is a burst signal of seconds. The spatial optical communication device according to claim 1.

6. A spatial optical communication device according to any one of claims 1 to 5, Equipped with a moving mechanism, A mobile object.

7. It is further equipped with an optical beacon section, The aforementioned optical beacon unit is equipped with multiple light sources that indicate orientation. The mobile body according to claim 6.

8. A spatial optical communication device according to any one of claims 1 to 5, Base station.

9. A mobile body comprising a spatial optical communication device according to any one of claims 1 to 5, A base station comprising a spatial optical communication device according to any one of claims 1 to 5, Equipped with, Communication system.

10. A spatial optical communication device that transmits a transmission optical signal to a communication target, receives a reception optical signal from the communication target, and communicates with the communication target, Movement mechanism, Optical beacon unit and equipment, The aforementioned spatial optical communication device is A transmitter that changes the direction of the light rays of the transmitted optical signal toward the communication target and transmits the transmitted optical signal to the communication target, A receiver that receives the received optical signal from the communication target, Equipped with, The aforementioned optical beacon unit is equipped with multiple light sources that indicate orientation. A mobile object.

11. The transmitter provided in the spatial optical communication device is A light generation unit that generates the aforementioned transmitted optical signal, An optical switching unit having an input optical waveguide into which the transmitted optical signal is input from the optical generation unit, a plurality of output optical waveguides, and an optical switch that switches and connects the input optical waveguide and the plurality of output optical waveguides, A lens provided outside the optical switching unit, into which light output from the plurality of output optical waveguides is incident, Equipped with, The spatial optical communication device switches the direction of the light rays of the transmitted optical signal by switching the output optical waveguide connected to the input optical waveguide using the optical switch. The mobile body according to claim 10.

12. A mobile body according to either Claim 10 or Claim 11, A base station comprising a spatial optical communication device according to any one of claims 1 to 5, Equipped with, Communication system.

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