Optical communication equipment

Abstract

The present invention provides an optical communication device that controls the receiving direction of a light beam using a single detector. [Solution] The optical communication device includes a reflective member 51 that reflects a light beam received via an optical antenna 50, and a light-receiving surface that is illuminated by the light beam reflected by the reflective member 51. The device includes a detection unit 1 that determines the light intensity distribution of the light beam illuminating the light-receiving surface for each of a plurality of incident angles with respect to the light-receiving surface, and detects the incident angle and incident position of the light beam based on the light intensity distribution determined for each of the plurality of incident angles, and a drive unit 55 that drives the reflective member based on the emission angle and emission position of the light beam.

Description

[Technical Field]

[0001] This disclosure relates to optical communication equipment used in free space optics (FSO) communication systems. [Background technology]

[0002] FSO communication is a communication method that transmits optical signals through free space rather than using a fixed medium such as optical fiber. In the following description, the optical signal transmitted into free space for FSO communication will be referred to as an "optical beam." In FSO communication, an optical communication device is configured to control the direction of reception of the optical beam so that the receiving direction of the optical beam is directed toward the direction of another optical communication device that is the communication partner of the optical communication device. Control of the reception direction of the optical beam is classified into coarse tracking control and fine tracking control. Coarse tracking control means controlling the direction of the optical antenna that focuses the light, and fine tracking control means controlling the position and direction of the optical components within the optical communication device, which is performed after the completion of coarse tracking control. Note that this disclosure focuses on fine tracking control, so the explanation of the configuration for coarse tracking control is omitted.

[0003] Figure 1 shows the configuration for precise tracking control disclosed in Non-Patent Literature 1. The optical antenna 50 focuses light and outputs it toward the mirror 51. The mirror 51 reflects the light beam from the optical antenna. The light beam reflected by the mirror 51 enters the branching unit 53 via the transmit / receive separation unit 52. The transmit / receive separation unit 52 has the function of separating the light beam to be transmitted to another optical communication device that is the communication partner from the light beam to be received from the other optical communication device.

[0004] The branching unit 53 outputs a portion of the incident light beam to the four-quadrant photodetector (QPD) 56 and outputs the remaining majority of the light beam to the branching unit 54. The branching unit 54 outputs a portion of the incident light beam to another QPD 57 and outputs the remaining majority of the light beam to the optical receiver that demodulates the light beam. Figure 2 shows the light incident surface of the QPD 56. The light incident surface of the QPD 57 is the same as that of the QPD 56. As shown in Figure 2, the QPD 56 has photodetectors 560 arranged in each of the four quadrants of the light incident surface, and outputs an electrical signal corresponding to the light reception power of each photodetector 560 as a detection result to the drive unit 55.

[0005] The drive unit 55 adjusts the position and angle of the mirror 51 based on the detection results from QPDs 56 and 57. Specifically, the drive unit 55 adjusts the position and angle of the mirror 51 so that the light received by the four photodetectors 560 of QPD 56 and the light received by the four photodetectors of QPD 57 are the same. The optical communication device is configured such that when the light received by the four photodetectors 560 of QPD 56 and the light received by the four photodetectors of QPD 57 are the same, the direction of the received light beam is directed toward the other optical communication device that is the communication partner. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Namiki Hashimoto, Hiroaki Shimizu, Masanori Morita, Daisuke Eto, Koichi Shiratama, Toshiaki Yamashita, Shigeru Murata, Development of a Capture and Tracking Terminal for Optical Space Communication, Laser Sensing Society, [online], accessed July 22, 2024, Internet.<URL:https: / / laser-sensing.jp / 29thLSS / 29th_papers / E-1.pdf> [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In the configuration described in Non-Patent Document 1, two detectors (two QPDs) are used for position and angle control. Therefore, at branching sections 53 and 54, it is necessary to output a portion of the received optical beam toward the detectors, which is equivalent to causing a loss in the optical beam input to the optical receiver. This loss of the optical beam affects the communication quality.

[0008] This disclosure provides a technique for controlling the receiving direction of a light beam with a single detector. [Means for solving the problem]

[0009] According to one aspect of the present disclosure, an optical communication device includes a reflective member that reflects a light beam received via an optical antenna, and a light-receiving surface that is illuminated by the light beam reflected by the reflective member, and includes detection means that determines the light intensity distribution of the light beam illuminating the light-receiving surface for each of a plurality of incident angles with respect to the light-receiving surface, and detects the incident angle and incident position of the light beam based on the light intensity distribution determined for each of the plurality of incident angles, and driving means that drives the reflective member based on the incident angle and incident position of the light beam. [Effects of the Invention]

[0010] According to this disclosure, the receiving direction of a light beam can be controlled with a single detector. [Brief explanation of the drawing]

[0011] [Figure 1] A diagram showing an example configuration for precise tracking control. [Figure 2] Cross-sectional view of QPD. [Figure 3] Configuration diagrams of optical communication devices according to several embodiments. [Figure 4] Diagrams illustrating the configuration of a detector according to several embodiments. [Figure 5] Diagrams illustrating the light-receiving section according to several embodiments. [Figure 6] Diagrams illustrating the configuration of a detector according to several embodiments. [Figure 7] Diagrams illustrating the configuration of a detector according to several embodiments. [Figure 8] Diagrams illustrating the configuration of a detector according to several embodiments. [Modes for carrying out the invention]

[0012] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the features described in the embodiments may be combined arbitrarily. Furthermore, identical or similar configurations will be given the same reference numeral, and redundant descriptions will be omitted.

[0013] <First Embodiment> Figure 3 shows the configuration for precise tracking control of an optical communication device according to this embodiment. The optical antenna 50 focuses light and outputs it toward the mirror 51, which is a reflective member. The mirror 51 reflects the light beam from the optical antenna. The light beam reflected by the mirror 51 enters the branching unit 53 via the transmit / receive separation unit 52. The transmit / receive separation unit 52 has the function of separating the light beam to be transmitted to another optical communication device that is a communication partner from the light beam to be received from the other optical communication device. If the optical antenna used for transmitting the light beam and the optical antenna used for receiving the light beam are different, and the optical paths of the transmitted light beam and the received light beam within the optical communication device do not overlap, the transmit / receive separation unit 52 may be omitted. The branching unit 53 outputs a portion of the incident light beam to the detector 1 and outputs the remaining majority of the light beam to the optical receiving unit that demodulates the light beam.

[0014] Figure 4 is a diagram showing the configuration of the detector 1 according to this embodiment. The light beam from the branching section 53 illuminates the light-receiving surface of the light-receiving section 10. Figure 5(A) is a plan view of the light-receiving surface of the light-receiving section 10. Hereinafter, the three mutually orthogonal directions in three-dimensional space will be referred to as the X direction, Y direction, and Z direction, and the light-receiving surface will be assumed to be parallel to the XY plane. Multiple grating couplers (GCs) 2 are arranged in a two-dimensional manner on the light-receiving surface of the light-receiving section 10.

[0015] Each GC2 outputs only light incident at a predetermined elevation angle and azimuth angle as output light to the intensity measuring unit 11. The elevation angle and azimuth angle of the incident direction of light that GC2 can output as output light are hereinafter referred to as "detected elevation angle" and "detected azimuth angle". As shown in Figure 5(B), in this disclosure, the elevation angle θ is defined as the angle with respect to the Z direction, which is parallel to the normal direction of the light receiving surface, rather than the angle with respect to the XY plane. The azimuth angle is based on the +Y direction. The detected azimuth angle of GC2 is determined by the direction of the grating of GC2. In Figure 5(A), GC2 is shown as an isosceles triangle, and each GC2 is assumed to receive and output light incident in the direction from its vertex toward the center of its base. In other words, the detected azimuth angle of all GC2 shown in Figure 5(A) is 0 degrees.

[0016] The detection elevation angle of GC2 is determined by the grating period, the wavelength of the light beam, etc. The detection elevation angle of each GC2 is shown above in Figure 5(A). According to Figure 5(A), the light receiving unit 10 has a detection elevation angle of θ1~θ N A GC2 is provided where N is an integer greater than or equal to 2. N The values ​​of each are different. Below, the detected elevation angle is θ. n Let K be the number of GC2s (where n is an integer from 1 to N) (where K is an integer greater than or equal to 2). In the following explanation, the detected elevation angle is θ. n A set of K GC2s is denoted as the nth set. Therefore, in this embodiment, a total of K × N GC2s are provided on the light-receiving surface.

[0017] A set of GC2s are arranged on the light-receiving surface in a dispersed manner so that the distribution of the light intensity on the light-receiving surface can be determined based on the output light from the GC2s in the set. In other words, the arrangement positions of each GC2 on the light-receiving surface are determined so that the same set of GC2s are not concentrated.

[0018] Returning to FIG. 4, the intensity measurement unit 11 measures the intensity (light intensity) of the output light from each GC2 and notifies the controller 12. In this embodiment, the light-receiving unit 10 and the intensity measurement unit 11 are integrally configured as a measurement unit 100. And the measurement unit 100 is configured to be rotatable around the rotation axis in the Z direction. The rotation drive unit 13 rotates the measurement unit 100 under the control of the controller 12.

[0019] In this embodiment, the rotation phase of the light-receiving surface shown in FIG. 5(A) is defined as the reference phase. When the rotation phase of the light-receiving surface is the reference phase, the detection azimuth angles of all the GC2s are 0 degrees, but by rotating the measurement unit 100, the detection azimuth angles of the GC2s can be changed.

[0020] The controller 12 sets the measurement unit 100 (light-receiving surface) to M different rotation phases so that the detection azimuth angles of each GC2 are φ1 to φ M (M is an integer of 2 or more), and measures the light intensity of the output light from a total of N×K GC2s at each rotation phase. The values of φ1 to φ M are all different. In the following description, when the detection azimuth angle of each GC2 is set to φ m (m is an integer from 1 to M), the light intensity of the output light from the k-th (k is an integer from 1 to K) GC2 among the K GC2s in the n-th set is denoted as I nm,k . Also, when the detection azimuth angle of each GC2 is set to φ m , the position of the k-th GC2 in the n-th set in the XY plane is denoted as (x nm,k , y nm,k ). The position (x nm,k , y nm,k ) of the k-th GC2 in the n-th set in the XY plane is different if the rotation phase of the light-receiving surface is different. Further, when the detection azimuth angle of each GC2 is φm When set to, the integrated value of the light intensities of the output lights from the K GC2s in the nth set, that is, Σ k I nm,k is defined as TI nm .

[0021] When the detection azimuth angle of each GC2 is set to φ m , the light intensities of the output lights from the K GC2s in the nth set are those indicating the light intensity distribution on the light-receiving surface (XY plane) of the component of the light beam incident on the light-receiving surface at the elevation angle θ n and the azimuth angle φ m . The integrated value TI nm indicates the intensity of the entire component of the light beam incident on the light-receiving surface at the elevation angle θ n and the azimuth angle φ m . In the following description, the elevation angle θ n and the azimuth angle φ m are also denoted as the elevation angle and the azimuth angle associated with the integrated value TI nm .

[0022] For example, assume that the elevation angle of the light beam incident on detector 1 is closest to θ P , and the azimuth angle is closest to φ Q . Note that θ P is any value of θ1 to θ N , and φ Q is any value of φ1 to φ M . In this case, among the total of N×M integrated values from TI 11 to TI NM , the maximum is the integrated value TI PQ . Therefore, the controller 12 determines the elevation angle θ PQ and the azimuth angle φ P associated with the maximum integrated value TI Q as the elevation angle and the azimuth angle of the light beam incident on detector 1. In the following description, the elevation angle and the azimuth angle of the light beam incident on detector 1 determined by the controller 12 are denoted as the "incident elevation angle" and the "incident azimuth angle".

[0023] The controller 12 sets the incident elevation angle and the incident azimuth angle to θ P and φQ When it is determined that it is I PQ,k , the maximum value of I is determined. For example, when I PQ,R is the maximum, the controller 12 determines the position of the light beam incident on the detector 1 in the XY plane as (x PQ,R , y PQ,R ). Note that R is any value from 1 to K. In the following description, the position of the light beam incident on the detector 1 determined by the controller 12 is referred to as the "incident position".

[0024] As the detection result of the light beam in the detector 1, the controller 12 outputs the incident elevation angle θ P , the incident azimuth angle φ R and the incident position (x PQ,R , y PQ,R ) to the drive unit 55. Note that the combination of the incident elevation angle θ P and the incident azimuth angle φ R is also referred to as the "incident angle" below. The optical communication device is configured such that when each of the incident angle and the incident position reaches a predetermined target value, the direction of the received light beam is most efficiently coupled to the light receiving unit and is directed toward another optical communication device that is the communication partner. As shown in FIG. 3, the drive unit 55 controls the position and angle of the mirror 51 such that each of the incident angle (the combination of the incident elevation angle and the incident azimuth angle) notified from the detector 1 and the incident position reaches a predetermined target value.

[0025] Note that in this embodiment, since all the detection azimuth angles of the GC2 when the light receiving surface is in the reference phase are the same, the detection azimuth angles φ1 to φ M for each of the first set to the Nth set are also the same. However, it is only necessary that the detection azimuth angles φ m of the same set of GC2 are the same, and the values of the detection azimuth angles φ m may be different if the sets are different. That is, if the detection azimuth angle of the GC2 of the nth set when the rotation phases of the light receiving surface are set to Φ1 to Φ M is denoted as φ 1n to φ Mn , the value of φ mn may be different for each set.

[0026] Furthermore, in this embodiment, the rotational phase of the light-receiving surface is Φ m The value of the detected azimuth angle φ of the K GC2s in the nth set when set to this value. m Although they were treated as the same, the rotational phase of the light-receiving surface was changed from Φ1 to Φ M By setting it to value φ1 to value φ M We just need to take each value, and the rotation phase of the light-receiving surface is Φ m When set to the same configuration, the detected azimuth angles of the K GC2s within the same set do not necessarily have to be the same. For example, the rotation phase Φ of the light-receiving surface. m Set it to (m × 2π) / M. Then, set the rotation phase of the light-receiving surface to Φ m When set to this configuration, the GC2s are configured such that the detection azimuth angle of the first GC2 in a set becomes (m × 2π) / M, and the detection azimuth angle of the second GC2 becomes {(m + 1) × 2π} / M. Even in this case, the rotation phase Φ of the light-receiving surface remains constant. m By setting the value to (1×2π) / M to (M×2π) / M, the detection azimuth angles of both the first and second GC2 in the set will be (1×2π) / M to (M×2π) / M, respectively, allowing the light intensity distribution at each detection azimuth angle to be determined.

[0027] As described above, the detector 1 has a light-receiving surface that is illuminated by a light beam reflected by a mirror 51, which is a reflective member, and determines the light intensity distribution on the light-receiving surface for each of several incident angles. Each incident angle is distinguished by a combination of the elevation angle with respect to the light-receiving surface and the azimuth angle, which is the angle with respect to a reference direction within the light-receiving surface. Based on the light intensity distribution determined for each of the multiple incident angles, the detector 1 detects the incident angle and incident position of the light beam. With this configuration, the receiving direction of the light beam can be controlled with a single detector.

[0028] For example, in this embodiment, in order to determine the light intensity distribution for each of several incident angles, multiple GC2s from the first set to the nth set are provided on the light-receiving surface. Each GC2 in each set is associated with a detected elevation angle and a detected azimuth angle, and is configured to receive and output light incident on the light-receiving surface at the detected elevation angle and the detected azimuth angle. GC2 is an example of a light-receiving member that receives and outputs light incident on the light-receiving surface at the detected elevation angle and the detected azimuth angle. In this embodiment, the detected elevation angle of the nth set of multiple GC2s (n is an integer from 1 to N) is set as the nth elevation angle, and the light-receiving surface is configured to rotate with its normal direction as the axis of rotation.

[0029] Detector 1 rotates the light-receiving surface so that the detection azimuth angles of the nth set of multiple GC2s are between the 1st azimuth angle and the Mth azimuth angle (where M is an integer greater than or equal to 2). When the light-receiving surface is illuminated by a light beam and the detection azimuth angle of the nth set of multiple GC2s is the mth azimuth angle (where m is an integer from 1 to M), the intensity of the output light emitted from the nth set of multiple GC2s is measured to determine the light intensity distribution at an incident angle of the nth elevation angle and the mth azimuth angle. In this embodiment, the detection azimuth angles of the first set of multiple GC2s to the Nth set of multiple GC2s were the same when the rotation phase of the light-receiving surface was the reference phase. However, the detection azimuth angles of at least one set of multiple GC2s when the rotation phase of the light-receiving surface is the reference phase may differ from the detection azimuth angles of at least one other set of multiple GC2s.

[0030] In this embodiment, the detector 1 calculates the integrated value of the light intensity distribution for each of the multiple incident angles and detects the incident angle of the light intensity distribution with the maximum integrated value as the incident angle of the light beam. The detector 1 also calculates the integrated value of the light intensity distribution for each of the multiple incident angles and detects the position of the light-receiving surface where the light intensity is maximum in the light intensity distribution with the maximum integrated value, that is, the position of the GC2 that output the output light with the maximum light intensity, as the incident position of the light beam.

[0031] <Second Embodiment> Next, the second embodiment will be described, focusing on the differences from the first embodiment. In the first embodiment, the integral value TI11 ~TI NM Based on the maximum value among them, the incident elevation angle and the incident azimuth angle were determined, and the incident position was determined based on the maximum value of each light intensity used to obtain the integrated value of the determined incident elevation angle and incident azimuth angle. Therefore, the determined incident elevation angle is one of θ1 to θ N and the determined incident azimuth angle is one of φ1 to φ M . That is, the resolution of the determined incident elevation angle and incident azimuth angle depends on the numbers of N and M. Similarly, the resolution of the incident position determined in the first embodiment depends on the arrangement density of GC2. This embodiment determines the incident elevation angle, the incident azimuth angle, and the incident position with a higher resolution than the first embodiment.

[0032] In this embodiment, the controller 12 obtains the center of gravity of the elevation angle and the center of gravity of the azimuth angle using the integrated value TI nm as weights, determines the center of gravity of the elevation angle as the incident elevation angle θ P , and determines the center of gravity of the azimuth angle as the incident azimuth angle θ Q . Specifically, the controller 12 obtains the integrated value TI n1 ~the integrated value TI nM by adding them, and obtains the integrated value TI n . Then, the controller 12 determines the incident elevation angle θ P as θ P =(Σ n TI n ×θ n ) / (Σ n TI n ). Similarly, the controller 12 obtains the integrated value TI 1m ~the integrated value TI Nm by adding them, and obtains the integrated value TI m . Then, the controller 12 determines the incident azimuth angle φ Q as φ Q =(Σ m TI m ×φ m ) / (Σ m TI m ).

[0033] Similar to the incident elevation angle and the incident azimuth angle, the controller 12 uses the light intensity I nm,kDetermine the centroid of the arrangement position of GC2 with weights, and determine that the centroid of the arrangement position is the incident position (x PQ,R , y PQ,R ). Specifically, the controller 12 determines the position x PQ,R in the X direction of the centroid of the arrangement position of GC2 as x PQ,R = (Σ n Σ m Σ k I nm,k × x nm,k ) / (Σ n Σ m Σ k I nm,k ). Similarly, the controller 12 determines the position y PQ,R in the Y direction of the centroid of the arrangement position of GC2 as y PQ,R = (Σ n Σ m Σ k I nm,k × y nm,k ) / (Σ n Σ m Σ k I nm,k ).

[0034] As described above, in this embodiment, the detector 1 obtains the integrated value of the light intensity distribution for each of a plurality of incident angles, and detects the centroid of the plurality of incident angles with the integrated value as the weight as the incident angle of the light beam. Further, the detector 1 determines the light intensity at each position of GC2 when GC2 outputs the output light based on the light intensity distribution for each of the plurality of incident angles, and detects the centroid of the position of GC2 with the light intensity as the weight as the incident position of the light beam. With this configuration, the incident angle and the incident position of the light beam can be detected with higher resolution than in the first embodiment.

[0035] <Third Embodiment> Subsequently, the third embodiment will be described focusing on the differences from the first and second embodiments. FIG. 6 is a configuration diagram of the detector 1 according to this embodiment. The difference from the configuration shown in FIG. 4 is that the light receiving unit 10 and the intensity measuring unit 11 are not integrally rotated by the rotation driving unit 13. Instead of rotating the light receiving unit 10, in this embodiment, in the nth set, the detection azimuth angles are φ1 to φ MK GC2s are provided in each set. In other words, the nth set contains a total of K × M GC2s. In the following explanation, among the K × M GC2s included in the nth set, the detected azimuth angle is φ m The K GC2s in the m subset are denoted as the m subset. Detector 1 measures the intensity of the output light emitted by the K GC2s in the m subset included in the n set, thereby determining the elevation angle θ. n and azimuth angle φ m The light intensity distribution at the incident angle is determined. The method for determining the incident angle and incident position of the light beam is the same as in the first and second embodiments. As also mentioned in the first embodiment, the detection azimuth angle φ of K GC2s included in the m-th subset of at least one set from the 1st to Nth sets is determined. m The value of is the detected azimuth angle φ of K GC2s that are included in the m-th subset of at least one other set. m The value may be different from the given value.

[0036] <Fourth Embodiment> Next, the fourth embodiment will be described, focusing on the differences from the first to third embodiments. Figure 7 shows an example of the configuration of the detector 1 according to this embodiment. Figure 7 shows the configuration shown in Figure 6 with the addition of a periodic control unit 14.

[0037] The detected elevation angle of GC2 depends on the grating period of GC2. Controller 2 controls the detected elevation angle of GC2 by controlling the grating period of GC2 via the period control unit 14. As an example, a heater that heats the light-receiving surface or each GC2 is provided in the light-receiving unit 10, and the period control unit 14 outputs a control signal to the heater to heat the heater. The grating period of GC2 changes due to thermal expansion caused by the heat of the heater. Controller 12 can control the detected elevation angle of GC2 by controlling the grating period of GC2 via the period control unit 14. In this case, controller 2 stores information in advance that shows the relationship between the current value supplied to the heater and the detected elevation angle of GC2. Alternatively, a micro-electromechanical system (MEMS) may be provided in each GC2, and the grating period of GC2 may be controlled by applying force to each GC2 using the MEMS.

[0038] By configuring the detection elevation angle of GC2 to be controllable, the number of detection elevation angles N of GC2 can be increased. Alternatively, instead of increasing the number of detection elevation angles N, the number of GC2s provided in the light receiving unit 10 can be reduced. For example, in the third embodiment, K × M GC2s were provided separately for the first set and K × M GC2s for the second set, but by controlling the detection elevation angle of GC2, the K × M GC2s can be used for both the first and second sets.

[0039] In this case, the detector 1 controls the grating period of K × M GC2s used in common by the first and second sets, thereby setting the detection elevation angle of the K × M GC2s to θ1, and the elevation angle θ1 and azimuth angle φ m The light intensity distribution at the incident angle is determined, and the grating period of the K × M GC2s is controlled to set the detected elevation angle of the K × M GC2s to θ2, thereby setting the elevation angle θ2 and azimuth angle φ m Determine the light intensity distribution at the angle of incidence.

[0040] Figure 7 shows the configuration of the third embodiment with the addition of a configuration for controlling the grating period of GC2, but the configuration of this embodiment can also be applied to the configuration of the first embodiment.

[0041] <Fifth Embodiment> Next, the fifth embodiment will be described, focusing on the differences from the first to fourth embodiments. In this embodiment, the light beam is obtained by wavelength multiplexing first to jth light beams (J being an integer of 2 or more) with different frequencies. In the following description, the frequency of the jth light beam (j being an integer from 1 to J) will be referred to as the jth frequency. Figure 8 shows an example of the configuration of the detector 1 according to this embodiment. Figure 8 shows the configuration shown in Figure 6 with the addition of a wavelength separation unit 15. The wavelength separation unit 15 has a wavelength separation member that corresponds one-to-one with the GC2 provided in the light receiving unit 10. The wavelength separation member separates the output light from the corresponding GC2 from the first frequency to the jth frequency and outputs the jth output light of the jth frequency to the intensity measuring unit 11.

[0042] The detection elevation angle of GC2 depends on the wavelength of light. Therefore, if the light beam is wavelength-multiplexed from the first to the Jth light beam, one GC2 can be considered to have J different detection elevation angles. Thus, as in the fourth embodiment, the number of detection elevation angles N can be increased. Alternatively, instead of increasing the number of detection elevation angles N, the number of GC2s provided in the light receiving unit 10 can be decreased.

[0043] For example, in the third embodiment, a first set of K × M GC2s and a second set of K × M GC2s were provided separately. However, if the light beam includes a first light beam of a first frequency and a second light beam of a second frequency, and the detected elevation angle of the K × M GC2s is θ1 for the first light beam and θ2 for the second light beam, then the K × M GC2s can be used for both the first and second sets. In this case, the detector 1 measures the intensity of the first output light to determine the elevation angle θ1 and azimuth angle φ m The light intensity distribution at the incident angle is determined, and the intensity of the second output light is measured, so that the elevation angle θ2 and azimuth angle φ m Determine the light intensity distribution at the angle of incidence.

[0044] Figure 8 shows the configuration of the third embodiment with the addition of a wavelength separation unit 15, but this embodiment is also applicable to the configurations of the first and fourth embodiments. Furthermore, although the optical beam is wavelength-multiplexed with first to Jth optical beams of different frequencies, it may also be time-division multiplexed with first to Jth optical beams.

[0045] With the above configuration, the receiving direction of the light beam can be controlled with a single detector. Therefore, it becomes possible to contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote sustainable industrialization and foster innovation." [Explanation of Symbols]

[0046] 51: Mirror, 1: Detector, 55: Drive unit

Claims

1. A reflective member that reflects the light beam received via an optical antenna, A detection means having a light-receiving surface that is illuminated by the light beam reflected by the reflective member, which determines the light intensity distribution of the light beam illuminating the light-receiving surface for each of a plurality of incident angles with respect to the light-receiving surface, and detects the incident angle and incident position of the light beam based on the light intensity distribution determined for each of the plurality of incident angles, A driving means for driving the reflecting member based on the incident angle and incident position of the light beam, An optical communication device equipped with the following features.

2. The light-receiving surface is provided with a first set of multiple light-receiving members to the Nth set of multiple light-receiving members (where N is an integer of 2 or more). The plurality of light-receiving members receive and output light incident on the light-receiving surface at the detected elevation angle and detected azimuth angle. The detected elevation angle of the nth set of multiple light-receiving elements (where n is an integer from 1 to N) is the nth elevation angle. The light-receiving surface is configured to be rotatable with respect to the direction normal to the light-receiving surface as the axis of rotation. The optical communication device according to claim 1, wherein the detection means rotates the light-receiving surface such that the detection azimuth angles of the n sets of the plurality of light-receiving members are the first azimuth angle to the M azimuth angle (where M is an integer of 2 or more), the light-receiving surface is illuminated by the light beam, and when the detection azimuth angle of the n sets of the plurality of light-receiving members is the m azimuth angle (where m is an integer from 1 to M), the intensity of the output light emitted from the n sets of the plurality of light-receiving members is measured to determine the light intensity distribution at the incident angle of the n elevation angle and the m azimuth angle.

3. The optical communication device according to claim 2, wherein the values ​​of the detected azimuth angles of the first set of multiple light-receiving members to the N sets of multiple light-receiving members are the same when the rotational phase of the light-receiving surface is the reference phase.

4. The optical communication device according to claim 2, wherein the value of the detected azimuth angle of at least one set of multiple light-receiving members when the rotational phase of the light-receiving surface is the reference phase is different from the value of the detected azimuth angle of at least one other set of multiple light-receiving members.

5. The light-receiving surface is provided with a first set of multiple light-receiving members to the Nth set of multiple light-receiving members (where N is an integer of 2 or more). The plurality of light-receiving members receive and output light incident on the light-receiving surface at the detected elevation angle and detected azimuth angle. The nth set of multiple light-receiving members (where n is an integer from 1 to N) includes the multiple light-receiving members of the first subset to the multiple light-receiving members of the Mth subset (where M is an integer of 2 or more), The detected elevation angle and detected azimuth angle of the multiple light-receiving members (where m is an integer from 1 to M) of the m subset included in the n set are the nth elevation angle and the m azimuth angle, The optical communication device according to claim 1, wherein the detection means determines the light intensity distribution at the incident angle of the n elevation angle and the m azimuth angle by measuring the intensity of the output light output from the plurality of light-receiving members of the m subset included in the n set when the light-receiving surface is irradiated by the light beam.

6. The optical communication device according to claim 5, wherein the value of the m azimuth angle of the m subset of at least one set is different from the value of the m azimuth angle of the m subset of at least one other set.

7. The optical communication device according to any one of claims 2 to 6, wherein each of the plurality of light-receiving members is a grating coupler.

8. The multiple first grating couplers in the first set and the second set are the same. The optical communication device according to claim 7, wherein the detection means controls the grating period of the plurality of first grating couplers to set the detection elevation angle of the plurality of first grating couplers to a first elevation angle and determines the light intensity distribution at the incident angle of the first elevation angle and the m azimuth angle, and controls the grating period of the plurality of first grating couplers to set the detection elevation angle of the plurality of first grating couplers to a second elevation angle and determines the light intensity distribution at the incident angle of the second elevation angle and the m azimuth angle.

9. The optical communication device according to claim 8, wherein the detection means controls the grating period of the plurality of first grating couplers by controlling the temperature of the plurality of first grating couplers.

10. The optical communication device according to claim 8, wherein the detection means controls the grating period of the plurality of first grating couplers by applying force to the plurality of first grating couplers.

11. The aforementioned light beam includes a first light beam of a first frequency and a second light beam of a second frequency. The multiple first grating couplers in the first set and the second set are the same. The detected elevation angles of the plurality of first grating couplers are the first elevation angle for light of the first frequency and the second elevation angle for light of the second frequency. The optical communication device according to claim 7, wherein the detection means separates the output light emitted by the plurality of first grating couplers into first output light of a first frequency and second output light of a second frequency, measures the intensity of the first output light to determine the light intensity distribution at an incident angle of a first elevation angle and m azimuth angle, and measures the intensity of the second output light to determine the light intensity distribution at an incident angle of a second elevation angle and m azimuth angle.

12. The optical communication device according to any one of claims 1 to 6, wherein the detection means obtains an integrated value of the light intensity distribution for each of the plurality of incident angles, and detects the incident angle of the light intensity distribution that maximizes the integrated value as the incident angle of the light beam.

13. The optical communication device according to any one of claims 1 to 6, wherein the detection means obtains the integrated value of the light intensity shown by the light intensity distribution for each of the plurality of incident angles, and detects the position of the light receiving surface where the light intensity is maximum in the light intensity distribution where the integrated value is maximum as the incident position of the light beam.

14. The optical communication device according to any one of claims 1 to 6, wherein the detection means obtains an integrated value of the light intensity distribution for each of the plurality of incident angles, and detects the centroid of the plurality of incident angles, with the integrated value as the incident angle of the light beam.

15. The optical communication device according to any one of claims 1 to 6, wherein the detection means determines the light intensity at each of the multiple positions on the light-receiving surface based on the light intensity distribution for each of the multiple incidence angles, and detects the centroid of the multiple positions, weighted by the light intensity, as the incidence position of the light beam.

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