Optical signal conversion device and optical signal calculation system

Abstract

To provide an optical signal conversion device that can convert an optical signal so as to enable grasping a phase state of each optical signal in order to enable control of the phase state of the optical signal.SOLUTION: An optical signal conversion device 100 is provided that comprises: two or more optical signal input lines 110 that input an optical signal; a multiplexing unit 120 that multiplexes the optical signals input from the two-or more optical signal lines 110; and one or more optical signal output lines 130 that output a newly generated optical signal in the multiplexing unit 120, in which the optical signal to be input from the two or more optical signal input lines 110 is output from the optical signal output line 130 as a different optical signal due to a difference in a refractive index during propagation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical signal conversion device and an optical signal computing system. [Background technology]

[0002] There is an optical signal converter that inputs optical signals from a plurality of optical input lines and outputs an internally combined optical signal. Non-Patent Document 1 discloses a technology in which M-channel optical input lines are combined with a 1-channel optical output line by a first-stage optical coupler, the 1-channel optical output line is branched into 3-channel optical output lines by an optical distributor, the 2-channel optical output lines after the branching are combined with the 1-channel optical output line by a second-stage optical coupler, and the optical output intensity after the combination is observed with a photodiode, thereby estimating the phase relationship of the input optical signals. It is known that when the phases of the optical signals input to each optical input line are all aligned, the output of the photodiode becomes maximum. Thus, by checking the maximum value of the photodiode output in advance, it is possible to determine whether the phase relationship of each current input signal is completely in phase. Then, based on whether the phase relationship is completely in phase, a parameter for correcting (controlling) the phase relationship can be estimated. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Tin Komljenovic and Paolo Pintus, “On-chip calibration and control of optical phased arrays”, Optics Express, Vol.26, No.3, 3199, 2018. Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology disclosed in Non-Patent Document 1, detailed phase information between each optical signal is lost due to the first-stage optical coupler. Due to the loss of phase information between optical signals, the phase state of each optical signal cannot be known individually and in detail. Therefore, due to the loss of phase information between optical signals, it becomes very difficult to accurately correct (control) the phase state of each optical signal individually.

[0005] The present invention has been made in consideration of the above points, and aims to provide an optical signal conversion device and an optical signal calculation system that convert optical signals so that the phase state of each optical signal can be grasped, in order to enable control of the phase state of the optical signals. [Means for solving the problem]

[0006] The optical signal conversion device of claim 1 of the present invention comprises two or more optical signal input sections for inputting optical signals, a multiplexing section for multiplexing the optical signals input from the two or more optical signal input sections, and one or more optical signal output sections for outputting optical signals newly generated within the multiplexing section, and the optical signals input from the two or more optical signal input sections are output from the optical signal output sections as different optical signals due to differences in refractive index during propagation.

[0007] A second aspect of the present invention provides the optical signal conversion device of the first aspect, wherein the multiplexing section includes one or more structures having a refractive index different from that of the multiplexing section.

[0008] A third aspect of the present invention provides the optical signal conversion device of the second aspect, wherein a plurality of the structures are randomly arranged inside the multiplexing section.

[0009] A fourth aspect of the present invention provides the optical signal conversion device of the third aspect, wherein the structure is made of materials of two or more different shapes or sizes, or materials having different refractive indices.

[0010] A fifth aspect of the present invention provides the optical signal conversion device of the first aspect, wherein each of the two or more optical signal input sections has at least a plurality of refractive indices or lengths.

[0011] A sixth aspect of the present invention provides an optical signal conversion device according to the fifth aspect, wherein at least one of the refractive index or the length of each of the two or more optical signal input sections is irregular or non-uniform.

[0012] A seventh aspect of the present invention provides an optical signal conversion device according to any one of the first to sixth aspects, wherein the multiplexing section has a higher refractive index than the surrounding area of ​​the multiplexing section.

[0013] The invention of claim 8 of the present invention is an optical signal conversion device of any of claims 1 to 7, wherein the multiplexing section is formed so that the distance from the surface to which the optical signal input section is connected to the surface to which the optical signal output section is connected is longer than the distance from the surface to which the optical signal input section is connected to the point at which the intensity of the optical signal is strongest or is relatively stronger than other points.

[0014] The invention of claim 9 is the optical signal conversion device of claim 8, wherein the shape of the surface of the multiplexing section to which the optical signal input section is connected is arc-shaped, and the shape of the surface to which the optical signal output section is connected is arc-shaped.

[0015] The invention of claim 10 of the present invention is an optical signal conversion device according to any one of claims 1 to 9, wherein the number of the optical signal output units is two or more, and at least one of the optical signal output units is connected to at least one of the optical signal input units.

[0016] The invention of claim 11 of the present invention is an optical signal conversion device of any of claims 1 to 10, further comprising a phase estimation unit that estimates a phase relationship of an optical signal input to the optical signal input unit based on the optical signal output from the optical signal output unit.

[0017] The invention of claim 12 of the present invention is the optical signal conversion device of claim 11, further comprising a phase control unit that controls the phase of the optical signal input to the optical signal input unit based on the result of the phase relationship estimation by the phase estimation unit.

[0018] The invention of claim 13 of the present invention is an optical signal conversion device of any of claims 1 to 10, further comprising a beam estimation unit that estimates the shape of a beam radiated from an antenna element connected upstream of the optical signal input unit, based on the optical signal output by the optical signal output unit.

[0019] The invention of claim 14 of the present invention is an optical signal conversion device of claim 13, further comprising a phase control unit that controls the phase of the optical signal input to the antenna element connected to the optical signal input unit based on the beam shape estimation result by the beam estimation unit.

[0020] An optical signal calculation system of claim 15 of the present invention comprises an optical signal conversion device according to any one of claims 1 to 10, a plurality of phase shifters which change the phases of a plurality of optical signals input to the optical signal conversion device, a phase control unit which determines parameters for determining the amount of phase shift of each of the phase shifters in accordance with the input signals, and a signal processing unit which uses an output of the optical signal conversion device to output a desired value related to the input signals. Effect of the Invention

[0021] According to the present invention, it is possible to provide an optical signal conversion device that converts optical signals so that the phase state of each optical signal can be grasped, in order to enable control of the phase state of the optical signals. [Brief description of the drawings]

[0022] [Figure 1] 1 is a diagram showing a schematic configuration of an optical signal conversion device according to an embodiment of the present invention; [Diagram 2] 11A and 11B are diagrams illustrating an example of a simulation of a result of combining optical signals by an optical signal conversion device. [Diagram 3] FIG. 1 is a diagram showing an example of the shape of a structure. [Figure 4] 1A and 1B are diagrams illustrating examples of the shape of a multiplexing section. [Diagram 5] FIG. 1 illustrates an example of the configuration of an optical signal conversion device. [Figure 6]1 is a diagram showing an example of the configuration of an optical beam control system including an optical signal conversion device according to an embodiment of the present invention; [Figure 7] FIG. 1 is a diagram illustrating a schematic configuration of an optical signal conversion device. [Figure 8] FIG. 1 is a diagram illustrating a schematic configuration of an optical signal conversion device. [Figure 9] FIG. 1 is a diagram for explaining an overview of reservoir computing. [Figure 10] 1 is a diagram illustrating an example of an optical signal conversion device according to an embodiment of the present invention. [Figure 11] 1A and 1B are diagrams illustrating examples of the shape of a multiplexing section. [Figure 12] 13A and 13B are diagrams illustrating other examples of the shape of the multiplexing portion. [Figure 13] 13A and 13B are diagrams illustrating other examples of the shape of the multiplexing portion. [Figure 14] 13A and 13B are diagrams illustrating other examples of the shape of the multiplexing portion. [Figure 15] 13A and 13B are diagrams illustrating other examples of the shape of the multiplexing portion. [Figure 16] 1 is a diagram showing an example of the configuration of an optical beam control system including an optical signal conversion device according to an embodiment of the present invention; [Figure 17] 1 is a diagram illustrating an example of the configuration of an optical signal calculation system including an optical signal conversion device according to an embodiment of the present invention. [Figure 18] 11 is a diagram illustrating an example of the relationship between the round trip time and the amplitude of a received signal when a pulsed signal is output. FIG. [Figure 19] FIG. 13 is a diagram showing how the presence or absence of an object is determined on a line in an image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same or equivalent components and parts are given the same reference numerals. In addition, the dimensional ratios of the drawings are exaggerated for the convenience of explanation and may differ from the actual ratios.

[0024] Fig. 1 is a diagram showing a schematic configuration of an optical signal conversion device according to this embodiment. In the present invention, the refractive index includes both the actual refractive index of a material and the effective refractive index seen from light. The effective refractive index may also be called the Effective Refractive Index, effective refractive index, or equivalent refractive index.

[0025] 1, optical signal conversion device 100 according to this embodiment includes a plurality of optical signal input lines 110, a multiplexing section 120 that multiplexes optical signals input from optical signal input lines 110, and a plurality of optical signal output lines 130 that output the optical signals multiplexed in multiplexing section 120. Optical signal conversion device 100 is a device that outputs optical signals input from optical signal input lines 110 from optical signal output lines 130 as different optical signals due to differences in refractive index during propagation.

[0026] The optical signal input line 110 is an example of the optical signal input section of the present invention. The optical signal input lines 110 each output an optical signal to the multiplexing section 120. The optical signal input line 110 is a physical line capable of propagating electromagnetic waves in the optical domain, and is made of a material having a higher refractive index than the surroundings. The optical signal input line 110 is made of, for example, an optical waveguide. Materials for the optical waveguide include Si, SiN, SiOx, LiNbO3, and the like. The optical signal input line 110 is made of, for example, a free space such as air or vacuum. The optical signal input line 110 is made of, for example, an optical fiber. The optical fiber can be made of glass or plastic. The multiple optical signals input to the multiplexing section 120 by the optical signal input line 110 may be in phase or may be different. FIG. 1 shows a state in which the multiple optical signals input to the multiplexing section 120 by the optical signal input line 110 all have different phases.

[0027] The multiplexing unit 120 multiplexes optical signals input from a plurality of optical signal input lines 110. The multiplexed optical signal is output from an optical signal output line 130, which will be described later. The multiplexing unit 120 has one or more structures 121 therein. The structures 121 act on the propagation of the multiplexed light, for example, by impeding the propagation of the multiplexed light, changing the propagation direction, or changing the propagation speed, thereby acting on the propagation of the multiplexed light. When a plurality of structures 121 are provided inside the multiplexing unit 120, the structures 121 are arranged randomly, not arranged with any regularity.

[0028] The multiplexing section 120 is made of a material and has a shape that allows an optical signal to be input from the optical signal input line 110 and allows light to propagate freely. The material of the multiplexing section 120 may be, for example, Si, SiN, SiOx, LiNbO3, or the like.

[0029] The structure 121 is made of a material and a shape capable of scattering light or changing the propagation direction, or a material and a shape capable of changing the propagation speed of light. The structure 121 may be formed of a material different from that of the multiplexing section 120 and may have a shape such as a perfect circle, an ellipse, a triangle, or a square. The structure 121 may also be a region in which two different materials are alternately arranged at a period shorter than the wavelength. The structure 121 may also be a region made of the same material as that of the multiplexing section 120 but with a different doping concentration. The structure 121 allows the optical signal input from the optical signal input line 110 to be output from the optical signal output line 130 as a different optical signal due to the difference in the refractive index during propagation.

[0030] The optical signal output line 130 is an example of the optical signal output unit of the present invention. The optical signal output line 130 is a physical line capable of propagating electromagnetic waves in the optical region, and is made of a material having a higher refractive index than the surroundings. The optical signal output line 130 is, for example, made of an optical waveguide. Examples of materials for the optical waveguide include Si, SiN, SiOx, and LiNbO3. The optical signal output line 130 is also made of free space such as air or vacuum. The optical signal output line 130 is, for example, made of an optical fiber. The optical fiber can be made of glass or plastic. The optical signal output by the optical signal output line 130 appears from the optical signal output line 130 as an optical signal having a unique strength and weakness due to the complex interference of the optical signal caused by the structure 121 inside the multiplexing section 120, which causes the optical signal to have a different refractive index during propagation.

[0031] A specific example of the optical signal conversion device 100 will be described. When the optical signal input line 110, the multiplexing section 120, and the optical signal output line 130 are all formed of the same material, for example, Si, the structure 121 can be formed of a material different from that of the multiplexing section 120, for example, SiN or SiOx. The structure 121 is formed of the same material as that of the multiplexing section 120 (Si in the above example), but can be a region having a different doping concentration from other regions of the multiplexing section 120. In this way, by forming the structure 121 of a material different from that of the multiplexing section 120 or by being a region having a different doping concentration from other regions of the multiplexing section 120, the optical signal input to the multiplexing section 120 is output from the multiplexing section 120 as a different optical signal due to the difference in the refractive index during propagation.

[0032] In FIG. 1, three optical signal output lines 130 are illustrated. When the optical signals output from the optical signal output lines 130 are received by the photodiodes 200A, 200B, and 200C, respectively, the strength relationship according to the phase relationship of the optical signal input from the optical signal input line 110 can be observed. FIG. 1 illustrates the strength relationship in each of the three phase relationships α, β, and γ. By inputting an optical signal to the optical signal conversion device 100 in a state in which the phase relationship of the input optical signal is known in advance, and measuring the strength relationship of the optical signal output from the optical signal conversion device 100, the relationship between the phase relationship and the strength relationship of the optical signal can be obtained. By obtaining the relationship between the phase relationship and the strength relationship of the optical signal in advance, when an optical signal with an unknown phase relationship is input to the optical signal conversion device 100, it becomes possible to estimate the phase relationship of the optical signal input to the optical signal conversion device 100 by measuring the strength relationship of the optical signal output from the optical signal conversion device 100.

[0033] Fig. 2 is a diagram showing a simulation example of the combining result of optical signals by the optical signal conversion device 100. Fig. 2(a) is a simulation example of the combining result in a state where there is no structure 121 in the multiplexing section 120. Fig. 2(b) is a simulation example of the combining result in a state where there is one structure 121 in the multiplexing section 120. Fig. 2(c) is a simulation example of the combining result in a state where there are two structures 121 in the multiplexing section 120.

[0034] When the structure 121 is not present inside the multiplexing unit 120, the input optical signals are uniformly multiplexed and output, as shown in Fig. 2(a). On the other hand, when the structure 121 is present inside the multiplexing unit 120, the input optical signals are not uniformly multiplexed, as shown in Fig. 2(b) and (c), and the structure 121 acts on the multiplexed waves, such as impeding propagation, changing the propagation direction, or changing the propagation speed. By acting on the progression of the multiplexed waves in this way, the optical signal output by the optical signal output line 130 appears as a signal with unique strengths and weaknesses.

[0035] 3 is a diagram showing an example of the shape of the structure 121. The shape of the structure 121 is not limited to a specific shape, such as a perfect circle, an ellipse, a rectangle, or a triangle, as long as it can realize the function of preventing the propagation of the multiplexed light or changing the propagation direction. In addition, the size of the structure 121 is not limited to a specific size, as long as it is large enough to allow a certain number of structures to be arranged inside the multiplexing unit 120 and the optical signal multiplexed inside the multiplexing unit 120 can be output from the optical signal output line 130.

[0036] FIG. 3(a) shows an example where the structures 121 are all perfect circles of the same size. FIG. 3(b) shows an example where the structures 121 are all perfect circles but of different sizes. FIG. 3(c) shows an example where the structures 121 are shaped like perfect circles and ellipses. FIG. 3(d) shows an example where the structures 121 are both different in shape and size. As shown in FIG. 3, the structures 121 may be formed in various shapes and sizes.

[0037] The shape of the multiplexing section 120 is also not limited to a specific shape as long as it has the function of multiplexing the optical signals input from the optical signal input lines 110. The shape of the multiplexing section 120 may be symmetrical in terms of the shape of the surface (input surface) to which the optical signal input lines 110 are connected and the shape of the surface (output surface) to which the optical signal output lines 130 are connected, or the input surface and the output surface may be asymmetrical. Furthermore, surfaces other than the input surface and the output surface may also be symmetrical or asymmetrical.

[0038] FIG. 4 is a diagram showing an example of the shape of the multiplexing unit 120. FIG. 4(a) shows an example in which the shape of the input surface and the shape of the output surface of the multiplexing unit 120 are symmetrical. FIG. 4(b) shows an example in which the shape of the multiplexing unit 120 is different from that of FIG. 4(a), but the shape of the input surface and the shape of the output surface are symmetrical. FIG. 4(c) shows an example in which the shape of the multiplexing unit 120 is elliptical. FIG. 4(d) shows an example in which the shape of the input surface and the shape of the output surface of the multiplexing unit 120 are symmetrical, and the shapes of the other surfaces are asymmetrical. FIG. 4(e) shows an example in which the shape of the multiplexing unit 120 is circular. FIG. 4(f) shows an example in which the shape of the multiplexing unit 120 is different from that of FIG. 4(a) and (b), but the shape of the input surface and the shape of the output surface are symmetrical. FIG. 4(g) shows an example in which the shape of the input surface and the shape of the output surface of the multiplexing unit 120 are asymmetrical. Fig. 4(h) shows an example in which the shape of the multiplexing section 120 is different from that of Fig. 4(d), but the shape of the input surface and the shape of the output surface are symmetrical, and the shapes of the other surfaces are asymmetrical. As shown in Fig. 4, the multiplexing section 120 may be formed in various shapes.

[0039] The optical signal conversion device 100 may input the optical signal output from the optical signal output line 130 again to the multiplexing section 120. By inputting the optical signal output from the optical signal output line 130 again to the multiplexing section 120, the optical signal conversion device 100 can perform optical signal conversion processing that reflects not only the current input but also the output from one time point before. One optical signal output line 130 may be connected to one optical signal input line 110, or one optical signal output line 130 may be split into two and used as input lines in different positions.

[0040] The optical signal conversion device 100 may be configured to recursively input the optical signal output from the multiplexing section 120 back to the multiplexing section 120 .

[0041] Fig. 5 is a diagram showing a configuration example of the optical signal conversion device 100. Fig. 5(a) shows an example in which one optical signal output line 130 is connected to the input surface of the multiplexing section 120. Fig. 5(b) shows an example in which one optical signal output line 130 is branched into two and connected to the input surface of the multiplexing section 120. Fig. 5(c) shows an example in which the optical signal output line 130 connected to the subsequent multiplexing section 120 is connected to the input surface of the previous multiplexing section.

[0042] As shown in FIG. 5, the optical signal conversion device 100 is configured to recursively input the optical signal output from the multiplexing section 120 back to the multiplexing section 120, thereby enabling it to perform optical signal conversion processing that reflects not only the current input signal but also the output signal from one instant earlier.

[0043] By using the optical signal conversion device 100, the phase relationship of a plurality of input optical signals can be inferred and used to control the phase of the input optical signals.

[0044] FIG. 6 is a diagram showing an example of the configuration of an optical beam control system including an optical signal conversion device 100 according to this embodiment.

[0045] The optical signal output from the laser diode 10 is divided and input to the phase shifter 20. The phase shifter may also be called a phase controller, a phase modulator, a phase shifter, or the like. The phase shifter 20 changes the phase of the optical signal output from the laser diode 10 by a predetermined amount. In the example of FIG. 6, the optical signal output from the laser diode 10 is divided into six. The phases of the optical signals output from each of the phase shifters 20 are φ1 to φ6, and are input to the antenna element 30. The antenna element 30 can change the direction (azimuth, angle) and shape of the beam radiated and formed from the antenna element 30 based on the phase relationship of the input optical signals. That is, the antenna element 30 functions as an optical scanner. This is called an optical phased array or optical phased array (OPA) type optical scanner.

[0046] When a part of the optical signal output from the antenna element 30 is input to the optical signal conversion device 100, the optical signal conversion device 100 outputs an optical signal in a state different from the input optical signal. The optical signal output from the optical signal conversion device 100 is received by a photodiode 200, and its intensity is detected. The intensity information of each optical signal is converted into digital information via a TIA (Transimpedance Amplifier) ​​40 and an A / D converter 50. Then, the intensity information of the optical signal output from the A / D converter 50 is input to a DNN (Deep Neural Network) 60. The DNN 60 is an example of a phase estimation unit of the present invention, and estimates and outputs the phase of the optical signal input to the optical signal conversion device 100 from the intensity information of the input optical signal. In the example of FIG. 6, the DNN 60 predicts the phases φ′1 to φ′6 of each of the six optical signals based on the input of the intensity information of the three optical signals.

[0047] The phase φ'n (n=1 to 6) predicted by the DNN 60 is input to the phase shifter controller 70. The phase shifter controller 70 is an example of a phase control unit of the present invention, and generates a correction parameter for correcting the phase of the optical signal output from the laser diode 10 based on the phase φ'n predicted by the DNN 60, thereby controlling the phase of the optical signal input to the optical signal conversion device 100. Specifically, the phase shifter controller 70 estimates the beam shape of the optical signal output from the antenna element 30 by applying the phase φ'n predicted by the DNN 60 to a table or conversion formula prepared in advance. Then, the phase shifter controller 70 generates a correction parameter from the estimated beam shape so that the desired beam shape is obtained. The phase shifter controller 70 outputs the generated correction parameter to the phase shifter 20. The phase shifter 20 corrects the phase of the optical signal output from the laser diode 10 based on the correction parameter generated by the phase shifter controller 70.

[0048] The user specifies the desired phase φ for the phase shifter 20. n Even if you intend to set the phase φ, it is difficult to set the exact phase due to various fluctuations in the circuit. nmay not be set in the phase shifter 20. n is not set in the phase shifter 20, light may be emitted in a direction different from that expected by the user, or the beam shape may be distorted. In such a case, if the phase relationship of the optical signals input to each antenna element can be known, the phase of the optical signal can be corrected by generating a correction parameter in the phase shifter controller 70.

[0049] 6 can predict the phase of an optical signal input to optical signal conversion device 100 by using the output of optical signal conversion device 100. This eliminates the need to observe the beam radiated from antenna element 30 with a camera, making it easier to correct the phase of the optical signal compared to observing the beam radiated from antenna element 30 with a camera.

[0050] Another configuration example of the optical signal conversion device will be described below. Fig. 7 is a diagram showing a schematic configuration of the optical signal conversion device.

[0051] Optical signal conversion device 150 shown in Fig. 7 includes optical signal input lines 160A to 160E, a multiplexing section 170, and optical signal output lines 180A to 180C. Similar to optical signal conversion device 100 shown in Fig. 1, optical signal conversion device 150 shown in Fig. 7 is a device that outputs an input optical signal as a signal having unique strength and weakness.

[0052] The optical signal input lines 160A-160E are an example of an optical signal input section of the present invention. The optical signal input lines 160A-160E each output an optical signal to the multiplexing section 170. The multiplexing section 170 multiplexes the optical signals input from the multiplexing section 160A-160E. The optical signal output lines 180A-180C are an example of an optical signal output section of the present invention, and output the optical signal multiplexed by the multiplexing section 170. The optical signal conversion device 150 shown in FIG. 7 includes five optical signal input lines 160A-160E and three optical signal output lines 180A-180C, but the numbers of optical signal input lines and optical signal output lines are not limited to this example.

[0053] The refractive index of the optical signal input lines 160A to 160E is one of a plurality of refractive indices. However, the refractive indexes of the optical signal input lines 160A to 160E are not all the same. For example, the optical signal input lines 160A, 160B, and 160D have a refractive index A, and the optical signal input lines 160C and 160E have a refractive index B that is different from the refractive index A.

[0054] Furthermore, the optical signal input lines 160A to 160E have one of a number of lengths. However, the optical signal input lines 160A to 160E are not all the same length. For example, the optical signal input lines 160A, 160B, and 160D have a length A, and the optical signal input lines 160C and 160E have a length B.

[0055] At least one or both of the refractive index or length of the optical signal input lines 160A-160E are irregular or non-uniform, so that the optical signal conversion device 150 can convert the input optical signal into a signal having a specific strength and weakness due to differences in the refractive index of the input optical signal and output the signal. Note that, as described above, the refractive index or length being irregular means that the refractive index or length of the optical signal input lines 160A-160E is one of a plurality of refractive indexes or lengths, and the refractive index or length being non-uniform means that the refractive indexes or lengths of the optical signal input lines 160A-160E are all different.

[0056] The optical signal input line is not limited to one having different refractive index or length, so long as it can output a signal having a unique strength from an input optical signal. Other examples of the optical signal input line will be described.

[0057] FIG. 8 is a diagram showing a schematic configuration of an optical signal conversion device.

[0058] Fig. 8(a) shows an example in which the optical signal input lines 160A to 160E have different thicknesses. By making the optical signal input lines 160A to 160E have different thicknesses, the optical signal conversion device 150 shown in Fig. 8(a) can output a signal having unique strengths and weaknesses.

[0059] Fig. 8(b) shows an example in which the materials or impurity concentrations of the optical signal input lines 160A to 160E are different. By making the materials or impurity concentrations of the optical signal input lines 160A to 160E different, the optical signal conversion device 150 shown in Fig. 8(b) can output a signal having unique strengths and weaknesses.

[0060] FIG. 8(c) shows an example in which a part or all of the optical signal input lines 160A-160E are changed to a submicron structure. In the optical signal input line 160A, the range indicated by reference numeral 161A is a submicron structure. Similarly, in the optical signal input line 160B, the range indicated by reference numeral 161B, in the optical signal input line 160C, the range indicated by reference numeral 161C, in the optical signal input line 160D, the range indicated by reference numeral 161D, and in the optical signal input line 160E, the range indicated by reference numeral 161E are each a submicron structure. By repeatedly arranging two or more structures at a period shorter than the wavelength of light, the apparent refractive index of the light propagating through the structure is between the refractive indexes of the two materials. By changing a part or all of the optical signal input lines 160A-160E to a submicron structure, the optical signal conversion device 150 shown in FIG. 8(c) can output a signal having a unique strength and weakness.

[0061] FIG. 8(d) shows an example in which a part or the whole of the optical signal input line is changed to a photonic crystal structure. The optical signal input line 160F has a photonic crystal structure. In a structure in which holes are regularly arranged, such as a photonic crystal, light is reflected and does not propagate. The photonic crystal structure acts as a wall, and the light propagates through the medium between the crystal structures as a waveguide. The refractive index changes depending on the arrangement of the crystal structures or the width of the waveguide. By changing a part or the whole of the optical signal input line to a photonic crystal structure, the optical signal conversion device 150 shown in FIG. 8(d) can output a signal with unique strengths and weaknesses.

[0062] By making a recursive connection as shown in FIG. 5, the optical signal conversion device according to this embodiment can be applied to the reservoir layer of reservoir computing.

[0063] Figure 9 is a diagram explaining the outline of reservoir computing. DNN (deep neural network) used in the field of deep learning consists of an input layer, multi-layered intermediate layers, and an output layer. DNN updates the weight coefficients of the artificial neurons in each layer so that a desired result is obtained for a certain input.

[0064] In contrast, in reservoir computing, the part equivalent to the intermediate layer is the reservoir layer. In the reservoir layer, artificial neurons (in this embodiment, the optical signal conversion devices 100 and 150) are recursively connected at random, and the weight coefficients of the reservoir layer are fixed.

[0065] When a laser light source that emits light based on an input signal is used as the input layer, the reservoir layer is composed of multiple optical signal conversion devices that are recursively connected at random, and the optical signal output from the optical signal conversion device is received by a photodiode. The area up to the laser light source is the electrical signal area, and the area from the laser light source to the photodiode is the optical signal area. The electrical signal output from the photodiode is added with a weighting coefficient by a circuit composed of an FPGA or the like, and the weighting coefficient is updated by taking the difference from the target value. In the example of Figure 9, the outputs from the three photodiodes are multiplied by weighting coefficients w1, w2, and w3, respectively.

[0066] Generally, when a physical device is fixed on a circuit, the coefficients are also fixed at the same time, making it difficult to apply it to DNNs that require coefficient updates. However, since the reservoir layer does not require weight updates, it can be realized even on physical devices with fixed coefficients.

[0067] By configuring the reservoir layer with the optical signal conversion device according to this embodiment, the processing speed is the speed of light, and the layer consumes almost no power. In addition, since weight updates by learning are only performed in the output layer, configuring the reservoir layer with the optical signal conversion device according to this embodiment has the effect of faster convergence of learning compared to DNN.

[0068] In the optical signal conversion device 100 according to this embodiment, the periphery of the multiplexing section 120 may be covered with a material having a lower refractive index than the material constituting the multiplexing section 120. By covering the periphery of the multiplexing section 120 with a material having a lower refractive index than the material constituting the multiplexing section 120, the optical signal conversion device 100 can confine light inside the multiplexing section 120 and prevent light from leaking outside the multiplexing section 120. By preventing light from leaking outside the multiplexing section 120, the optical signal conversion device 100 can reduce loss due to the multiplexing section 120.

[0069] 10 is a diagram showing an example of an optical signal conversion device 100 according to this embodiment. In the example shown in FIG. 10, the periphery of the multiplexing section 120 is covered with a material 122 having a lower refractive index than the material constituting the multiplexing section 120. The area covered with the material 122 needs only to cover the entire multiplexing section 120. When Si is used as the material of the multiplexing section 120, the material 122 is SiO x For example, SiO2 may be used. In addition, when Si3N4 is used as the material of the multiplexing section 120, the substance 122 may be SiO x For example, SiO2 may be used. When Si, Si3N4, or LiNbO3 is used as the material of the multiplexing section 120, the substance 122 may be air.

[0070] As described above, the multiplexing section 120 of the optical signal conversion device 100 according to this embodiment can have various shapes. Possible shapes of the multiplexing section 120 will be further described.

[0071] FIG. 11 is a diagram showing an example of the shape of the multiplexing unit 120. When light is input to the multiplexing unit 120, a point inside the multiplexing unit 120 where the light is strongest or a point where the light is relatively stronger than the surroundings is defined as a strong intensity point. The strong intensity point can be obtained by performing a simulation at the time of design. An example of a simulation method is the finite-difference time-domain (FDTD) method. As shown in FIG. 11, the multiplexing unit 120 may be shaped such that the distance from the input portion of the optical signal of the multiplexing unit 120 to the strong intensity point is longer than the distance from the input portion of the optical signal of the multiplexing unit 120 to the output portion of the optical signal of the multiplexing unit 120.

[0072] The input signals for checking the strong intensity points may all be the same. Alternatively, the phase of each input signal may be appropriately changed while checking the occurrence positions of the strong intensity points, and the shape may be such that the distance from the input portion of the optical signal of the multiplexer 120 to the strong intensity point occurring at the farthest position from the side wall of the input portion is longer than the distance from the input portion of the optical signal of the multiplexer 120 to the output portion of the optical signal of the multiplexer 120.

[0073] FIG. 12 is a diagram showing another example of the shape of the multiplexing unit 120. The shape of the side wall of the input part of the optical signal of the multiplexing unit 120 may be an arc shape. The circle of the arc may be a perfect circle, or may be an outwardly convex curve such as an ellipse or a clothoid curve. The shape of the side wall of the output part of the optical signal of the multiplexing unit 120 may be an arc shape. The circle of the arc may be a perfect circle, or may be an outwardly convex curve such as an ellipse or a clothoid curve. The shape of the side wall of the input part of the optical signal of the multiplexing unit 120 and the shape of the side wall of the output part may be the same shape or different shapes. As shown in FIG. 12, the multiplexing unit 120 may be shaped such that the distance from the input part of the optical signal of the multiplexing unit 120 to the center of the arc circle is longer than the distance from the input part of the optical signal of the multiplexing unit 120 to the output part of the optical signal of the multiplexing unit 120.

[0074] Here, a case is shown in which the distance from the input portion of the optical signal of the multiplexing unit 120 to the center of the arc circle is shorter than the distance from the center to the output portion of the optical signal of the multiplexing unit 120. FIG. 13 is a diagram showing another example of the shape of the multiplexing unit 120. FIG. 13(a) shows an example in which the arc of the output portion of the multiplexing unit 120 overlaps with the center of the arc of the input portion of the optical signal of the multiplexing unit 120. The center of the arc circle is the point where the light input from the input portion is most likely to gather. In this case, there is a possibility that the light output from the output portion will be biased. Therefore, a shape in which the distance from the input portion of the optical signal of the multiplexing unit 120 to the center of the arc circle is 0 or is extremely short compared to the distance from the center to the output portion of the optical signal of the multiplexing unit 120 is not preferable.

[0075] Fig. 13(b) shows an example in which the distance from the optical signal input port of the multiplexing unit 120 to the center of the circular arc is longer than the distance from the center to the optical signal output port of the multiplexing unit 120. As shown in Fig. 13(b), by making the distance from the center to the optical signal output port of the multiplexing unit 120 longer than the distance from the optical signal input port of the multiplexing unit 120 to the center of the circular arc, the light is appropriately dispersed inside the multiplexing unit 120, and an output result with less bias can be obtained.

[0076] However, it is not enough to simply increase the distance from the center of the arc to the optical signal output portion of the multiplexing unit 120. If the distance from the center of the arc to the optical signal output portion of the multiplexing unit 120 becomes too long, the optical signal spreads too much, and there is a possibility that it will not be output efficiently.

[0077] FIG. 14 is a diagram showing another example of the shape of the multiplexing unit 120. FIG. 14(a) shows an example in which the distance from the input portion of the optical signal of the multiplexing unit 120 to the center of the circular arc is longer than the distance from the center to the output portion of the optical signal of the multiplexing unit 120. As shown in FIG. 14(a), if the distance from the center of the circular arc to the output portion of the optical signal of the multiplexing unit 120 becomes too long, a part of the optical signal may be reflected by a side wall near the output portion and return to the inside or leak out of the multiplexing unit 120 before the optical signal reaches the output portion of the multiplexing unit 120. Also, as shown in FIG. 14(b), if the distance from the center of the circular arc to the output portion of the optical signal of the multiplexing unit 120 is further increased, the possibility that a part of the optical signal may be reflected by a side wall near the output portion and return to the inside or leak out of the multiplexing unit 120 before the optical signal reaches the output portion of the multiplexing unit 120 increases further. Therefore, it is desirable that the distance from the center of the arc circle to the output portion of the optical signal of the multiplexing section 120 be a distance that prevents the optical signal from being reflected by the side wall and returning to the inside, or leaking out of the multiplexing section 120.

[0078] Further another example of the shape of the multiplexing section 120 is shown. FIG. 15 is a diagram showing an example of the shape of the multiplexing section 120. As shown in FIG. 15(a), the multiplexing section 120 may have a shape in which the side surface of the multiplexing section 120 excluding the input and output sections is convex inward (concave outward). By making the side surface of the multiplexing section 120 excluding the input and output sections convex inward, it is possible to increase the possibility that the optical signal incident from the input section of the multiplexing section 120 can be reflected at an obtuse angle by the upper and lower side walls. This makes it easier for the optical signal to be totally reflected inside the multiplexing section 120, and makes it easier to confine the optical signal inside the multiplexing section 120. In addition, as shown in FIG. 15(b), the multiplexing section 120 may have a shape in which the side surface of the multiplexing section 120 excluding the input and output sections is convex inward, and the width of the multiplexing section 120 widens toward the output section.

[0079] In the optical beam control system including the optical signal conversion device 100 described above, the phase is predicted by the DNN, and a correction parameter is generated based on the predicted phase to correct the phase of the optical signal output from the laser diode 10. However, the method of generating the correction parameter is not limited to this example.

[0080] Fig. 16 is a diagram showing an example of the configuration of an optical beam control system including an optical signal conversion device 100 according to this embodiment. The optical beam control system shown in Fig. 16 corrects the phase of the optical signal output from the laser diode 10 by a phase shifter 20, similar to the optical beam control system shown in Fig. 6. The optical beam control system shown in Fig. 16 differs from the optical beam control system shown in Fig. 6 in that a correction parameter for correcting the phase of the optical signal output from the laser diode 10 by a phase shifter controller 75 is generated based on the estimated beam form (FFP') output by the DNN 65.

[0081] The DNN 65 is an example of the beam estimation unit of the present invention, and is a neural network previously trained to estimate and output the shape (beam form) of the beam of the optical signal emitted from the antenna element 30 from the intensity information of the input optical signal. In addition to the intensity information of the optical signal, temperature information measured by the temperature sensor 45 may be input to the DNN 65. The temperature measured by the temperature sensor 45 may be at least one or more of the temperature of the chip on which the optical beam control system is mounted, the temperature of the phase shifter 20, the temperature of the optical signal conversion device 100, and the temperature of the antenna element 30. Since the characteristics of the optical signal conversion device 100 may change due to the influence of temperature, inputting temperature information to the DNN 65 enables estimation of the beam form according to the temperature.

[0082] In addition to the information on the intensity of the optical signal and the information on the temperature measured by the temperature sensor 45, information on the emission wavelength of the laser diode 10 may be input to the DNN 65. When the emission wavelength of the laser diode 10 is constant, a set value of the emission wavelength is input to the DNN 65 as information on the emission wavelength of the laser diode 10, and when the emission wavelength of the laser diode 10 is not constant, an actual value of the wavelength of the light of the laser diode 10 measured by a wavelength measuring device or the like is input to the DNN 65.

[0083] The optical beam control system shown in FIG. 16 can estimate the beam shape of the optical signal radiated from the antenna element 30 from the optical signal output from the optical signal conversion device 100, even without a dedicated imaging device for knowing the beam shape of the optical signal radiated from the antenna element 30.

[0084] Another application example of the optical signal conversion device 100 is shown. FIG. 17 is a diagram showing an example of the configuration of an optical signal calculation system including the optical signal conversion device 100 according to this embodiment. The optical signal calculation system shown in FIG. 17 is a system that calculates the frequency of a time waveform signal, such as a sound wave, when the time waveform signal is input. Generally, a process with high computational costs, such as a Fourier transform process, is required to calculate the frequency of the time waveform signal. The optical signal calculation system shown in FIG. 17 is a system that makes it possible to output the frequency of a time waveform signal without requiring such a process with high computational costs.

[0085] The time waveform signal is detected by a sensor 76, and the phase shifter controller 77 samples the time waveform signal by the number of phase shifters 20. The sampling results are used to calculate a control parameter (e.g., a voltage V φm ) is output from the phase shifter controller 77 to the phase shifter 20. That is, the phase shifter controller 77 changes the intensity information of the time waveform signal into phase information.

[0086] 17, the optical signal output from the laser diode 10 is divided into M parts. The phases of the optical signals output from the phase shifters 20 are set to φ1 to φ2 by the control parameters. M Assume that the phase shifter 20 is set to the phase shifter 20. The optical signals output from each of the phase shifters 20 are input to the optical signal converter 100. Inside the optical signal converter 100, the optical signals interfere in a complex manner. Then, the optical signals are output from the output lines of the optical signal converter 100. The optical signals output from the optical signal converter 100 are received by the photodiode 200, and the intensity is detected. The intensity information of each optical signal is converted into digital information via the TIA 40 and the A / D converter 50. Then, the intensity information of the optical signal output from the A / D converter 50 is input to the signal processor 67. The signal processor 67 is preferably a pre-training type signal processor that has previously trained the relationship between the output of the optical signal converter 100 and the frequency of the time waveform signal. The pre-training type signal processor may be a simple one using a single artificial neuron (simple perceptron), or may be an advanced one using a DNN. Furthermore, the signal processor is not limited to techniques related to neural networks, and may use machine learning techniques in a broad sense, such as linear regression, decision trees, and support vector machines.

[0087] The optical signal conversion device 100 can be applied not only to a system that outputs the frequency of a time waveform signal, but also to a TOF (Time Of Flight) method in which a pulsed signal is irradiated toward an object and the distance to the object is calculated from the round-trip time from the start of the signal irradiation until the signal bounces off the object and returns. FIG. 18 is a diagram showing an example of the relationship between the round-trip time and the amplitude of a received signal when a pulsed signal is output. The TOF method is a technique for detecting the distance to an object from information on the round-trip time in which the amplitude is detected. By using the optical signal conversion device 100, it is possible to omit the process of searching for the location of the reflected pulse.

[0088] Moreover, the optical signal conversion device 100 is not limited to a time signal that changes with time, but is applicable to a system in general that receives a one-dimensional vector signal as an input and performs a determination process based on the signal. For example, the optical signal conversion device 100 is also applicable to an image processing system that receives a signal of one or more lines of an image as an input and determines whether a specific object exists on the line. FIG. 19 is a diagram showing a state in which one line of an image is extracted and the presence or absence of an object on the line is determined based on the relationship between the image position and intensity (brightness) on the line. By sampling the relationship between the image position and intensity (brightness) and providing the control parameter generated from the sampling result to the phase shifter 20, an optical signal according to the sampling result can be output from the optical signal conversion device 100. Then, similarly to the optical signal calculation system shown in FIG. 17, by using a signal processor that is trained in advance to receive information on the intensity of an optical signal and output the presence or absence of an object, it is possible to output the presence or absence of an object on the line from the signal of one line of an image. Furthermore, the present invention is not limited to the method of generating a one-dimensional signal by cutting out a part of a two-dimensional signal as described above, but may also use a multidimensional signal of two or more dimensions for input. Furthermore, the input signal may be a one-dimensional signal obtained by converting the shape of a two- or higher-dimensional multidimensional signal itself into a one-dimensional signal.

[0089] As described above, according to this embodiment, an optical signal conversion device is provided that outputs an optical signal having a unique strength due to differences in the refractive index during propagation from optical signals inputted through a plurality of optical signal input lines. It is possible to estimate the phase relationship of the input optical signals from information on the strength of the optical signals outputted by the optical signal conversion device according to this embodiment. [Explanation of symbols]

[0090] 100 Optical signal conversion device 110 Optical signal input line 120 Multiplexing section 121 Structure 130 Optical signal output line 150 Optical signal conversion device 160A, 160B, 160C, 160D, 160E Optical signal input line 170 Combined Wave Department 180A, 180B, 180C optical signal output line

Claims

1. Two or more optical signal input units for inputting optical signals; a multiplexing unit that multiplexes the optical signals input from the two or more optical signal input units; two or more optical signal output units for outputting optical signals newly generated in the multiplexing unit; a phase estimator that estimates a phase relationship of an optical signal input to the optical signal input unit based on an optical signal output from the optical signal output unit; Equipped with the optical signals inputted from the two or more optical signal input units are outputted from the optical signal output unit as different optical signals due to a difference in refractive index during propagation, At least one of the optical signal outputs is connected to at least one of the optical signal inputs.

2. 2. The optical signal conversion device according to claim 1, wherein the multiplexing section includes one or more structures having a refractive index different from that of the multiplexing section.

3. 3. The optical signal conversion device according to claim 2, wherein a plurality of said structures are randomly arranged inside said multiplexing section.

4. 4. The optical signal conversion device according to claim 3, wherein the structure is made of materials having two or more different shapes or sizes, or materials having different refractive indices.

5. 2. The optical signal conversion device according to claim 1, wherein each of the two or more optical signal input sections has at least a plurality of refractive indices or lengths.

6. 6. The optical signal conversion device according to claim 5, wherein at least one of a refractive index or a length of each of the two or more optical signal input sections is irregular or non-uniform.

7. 7. The optical signal conversion device according to claim 1, wherein the multiplexing section has a higher refractive index than the surrounding area of ​​the multiplexing section.

8. The optical signal conversion device according to any one of claims 1 to 7, wherein the multiplexing section is formed so that the distance from the surface to which the optical signal input section is connected to the surface to which the optical signal output section is connected is longer than the distance from the surface to which the optical signal input section is connected to the point at which the intensity of the optical signal is strongest or relatively stronger than other points.

9. 9. The optical signal conversion device according to claim 8, wherein the surface of said multiplexing section to which said optical signal input section is connected has an arc shape, and the surface to which said optical signal output section is connected has an arc shape.

10. 2. The optical signal conversion device according to claim 1, further comprising a phase control section that controls a phase of the optical signal input to said optical signal input section based on a result of the phase relationship estimated by said phase estimating section.

11. An optical signal conversion device according to any one of claims 1 to 10, further comprising a beam estimation unit that estimates a shape of a beam of an optical signal radiated from an antenna element connected in front of the optical signal input unit based on the optical signal output from the optical signal output unit.

12. 12. The optical signal conversion device according to claim 11, further comprising a phase control unit that controls a phase of the optical signal input to the antenna element connected to the optical signal input unit based on a result of the beam shape estimation by the beam estimation unit.

13. An optical signal conversion device according to any one of claims 1 to 9, a plurality of phase shifters for changing the phases of a plurality of optical signals input to the optical signal conversion device; a phase control unit that determines a parameter for determining the amount of phase shift of each of the phase shifters in response to an input signal; a signal processing unit that uses an output of the optical signal conversion device to output a desired value related to the input signal; An optical signal computation system comprising:

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