Optical multiplexing arithmetic circuit and distance measuring device

Abstract

This optical multiplexing arithmetic circuit comprises a code multiplexing circuit, an adding circuit, a correlation circuit, and a control circuit. The code multiplexing circuit can perform code multiplexing and amplification on a plurality of optical signals, thereby generating a plurality of first modulated optical signals. The adding circuit can add together a plurality of reflected optical signals obtained as a response to the transmission of the plurality of first modulated optical signals, thereby generating an added optical signal. The correlation circuit can calculate a correlation between the added optical signal and a plurality of code strings used for the code multiplexing, for each code string, thereby generating a plurality of correlation signals. The control circuit can control the code multiplexing circuit such that the signal power-to-interference power ratios of the correlation signals are approximately equal to each other.

Description

Optical multiplexing circuit and distance measuring device

[0001] This disclosure relates to an optical multiplexing circuit and a distance measuring device.

[0002] A distance measuring device is known that detects the condition of a target area based on the reflected light when a single beam of light (outgoing light) is shone onto the target area.

[0003] Japanese Patent Publication No. 2012-093195

[0004] Incidentally, when the target is in close proximity to the rangefinder, high-intensity reflected light enters the photodetector within the rangefinder. In this case, the photodetector may become saturated, potentially reducing the accuracy of distance measurement to the target. Therefore, it is conceivable to adjust the intensity of a single emitted light according to the intensity of the reflected light. However, when multiple emitted lights are simultaneously directed towards the target area, interference between multiple reflected lights obtained from the multiple emitted lights may reduce the accuracy of distance measurement to the target. It is desirable to provide an optical multiplexing circuit capable of adjusting interference between multiple reflected lights, and a rangefinder equipped with such an optical multiplexing circuit.

[0005] An optical multiplexing circuit according to one aspect of this disclosure comprises a code multiplexing circuit, a transceiver circuit, an adder circuit, a correlation circuit, and a control circuit. The code multiplexing circuit is capable of modulating each of a plurality of optical signals with a different code sequence for each optical signal and amplifying them independently, thereby generating a plurality of first modulated optical signals. The transceiver circuit is capable of transmitting the plurality of first modulated optical signals to the external space. The transceiver circuit is further capable of receiving a plurality of reflected optical signals from the external space as a response to the transmission to the external space. The adder circuit is capable of adding the plurality of reflected optical signals and thereby generating an added optical signal. The correlation circuit is capable of calculating the correlation between the added optical signal and a plurality of code sequences for each code sequence and thereby generating a plurality of correlated signals. The control circuit is capable of controlling the code multiplexing circuit so that the signal power to interference power ratio of each correlated signal is approximately the same.

[0006] A distance measuring device relating to one aspect of this disclosure comprises the above-described optical multiplexing circuit and a signal processing circuit. The signal processing circuit is capable of deriving the position and distance of a target by signal processing using a plurality of signals obtained by the above-described optical multiplexing circuit.

[0007] Figure 1 is a diagram showing an example of the functional block of an optical multiplexing circuit according to the first embodiment of this disclosure. Figure 2 is a diagram showing an example of the cross-sectional structure of the optical multiplexing circuit of Figure 1. Figure 3 is a diagram showing an example of the circuit configuration of the modulation circuit of Figure 1. Figure 4 is a diagram showing an example of the schematic configuration of the transmitting and receiving circuit of Figure 1. Figure 5 is a diagram showing an example of the relationship between multiple transmitted light outputs from the transmitting and receiving circuit of Figure 1 and multiple received light incident on the transmitting and receiving circuit of Figure 1. Figure 6 is a diagram showing an example of the relationship between multiple received light incident on the receiving circuit of Figure 4 and the laser light output from the receiving circuit of Figure 4. Figure 7 is a diagram showing an example of the circuit configuration of the detection circuit of Figure 1. Figure 8 is a diagram showing an example of the circuit configuration of the correlation circuit of Figure 1. Figure 9 is a diagram showing an example of correlation processing in the correlation circuit of Figure 8. Figure 10 is a diagram showing an example of the output of the correlation circuit of Figure 8. Figure 11 is a diagram showing an example of the output of the correlation circuit of Figure 8. Figure 12 is a diagram for explaining the signal power before and after correlation processing in Comparative Example A. Figure 13 is a diagram illustrating the signal power before and after correlation processing in Comparative Example B. Figure 14 is a diagram illustrating the signal power before and after correlation processing in this embodiment. Figure 15 is a diagram showing an example of the functional block of an optical multiplexing circuit according to the second embodiment of this disclosure. Figure 16 is a diagram showing an example of the cross-sectional structure of the optical multiplexing circuit in Figure 15. Figure 17 is a diagram showing an example of the functional block of a distance measuring device according to the third embodiment of this disclosure. Figure 18 is a block diagram showing an example of the schematic configuration of a vehicle control system. Figure 19 is an explanatory diagram showing an example of the installation positions of the external information detection unit and the imaging unit.

[0008] <Background> Distancing devices are known that detect the conditions of a target area based on the reflected light when a single laser beam is shone onto the target area. Generally, a distance measuring device scans a single laser beam within the target area and detects the presence or absence of obstacles at each scan position based on the presence or absence of reflected light at each scan position. Furthermore, the distance to obstacles at each scan position is detected based on the time elapsed from the laser beam irradiation timing to the reflected light reception timing at each scan position.

[0009] Reflected light from the target area is received by a photodetector in the rangefinder. The photodetector outputs a signal of a magnitude corresponding to the amount of light received. When this signal exceeds a predetermined threshold, it is determined that an obstacle is present at the scan location. Based on the timing at which this signal exceeds the threshold, the distance to the obstacle at the scan location is measured.

[0010] Incidentally, when the target is in close proximity to the rangefinder, high-intensity reflected light enters the photodetector. In this case, the photodetector may become saturated, potentially reducing the accuracy of distance measurement to the target. Therefore, it is conceivable to adjust the intensity of a single laser beam according to the intensity of the reflected light. However, when multiple laser beams are simultaneously irradiated toward the target area, interference between multiple reflected light beams obtained from multiple emitted beams may reduce the accuracy of distance measurement to the target. It is desirable to provide an optical multiplexing circuit capable of adjusting interference between multiple reflected light beams, and a rangefinder equipped with such an optical multiplexing circuit.

[0011] The embodiments for implementing this disclosure will be described in detail below with reference to the drawings. The following description is one specific example of this disclosure, and this disclosure is not limited to the embodiments described below. The description will be given in the following order: 1. First Embodiment (Figures 1 to 14) 2. Second Embodiment (Figures 15 and 16) 3. Third Embodiment (Figure 17) 4. Application Example (Figures 18 and 19)

[0012] <1. First Embodiment> [Configuration Example] First, the configuration of the optical multiplexing circuit 1 according to the first embodiment of the present disclosure will be described. Figure 1 shows an example of the functional blocks of the optical multiplexing circuit 1. Figure 2 shows an example of the cross-sectional structure of the optical multiplexing circuit 1. The optical multiplexing circuit 1 includes, for example, an optical circuit 10 and an electrical circuit 20, as shown in Figure 1.

[0013] The optical circuit 10 is provided within the substrate 10A, for example, as shown in Figure 2. The electrical circuit 20 is provided within the substrate 20A, for example, as shown in Figure 2. The substrates 10A and 20A are laminated together by so-called hybrid bonding, for example, as shown in Figure 2. Hybrid bonding refers to a strong intermolecular bond between the insulating film (e.g., silicon oxide) on the surface of the substrate 10A and the insulating film (e.g., silicon oxide) on the surface of the substrate 20A, and a metallic bond between multiple copper (Cu) pads on the surface of the substrate 10A and multiple Cu pads on the surface of the substrate 20A. The multiple Cu pads used in hybrid bonding constitute part of the wiring that electrically connects the optical circuit 10 and the electrical circuit 20.

[0014] The optical circuit 10 includes, for example, a laser light source 11 and a splitter 12, as shown in Figures 1 and 2. The laser light source 11 is configured to include a semiconductor laser capable of emitting a single laser beam L1 with a central wavelength λ. The central wavelength λ is, for example, a wavelength in the near-infrared region. The laser light source 11 may be provided separately from the substrate 10A, for example. The laser light source 11 may be mounted on the surface of the substrate 20A, for example, so that the laser beam L1 can be irradiated onto the side surface of the substrate 10A. The splitter 12 is an optical component capable of splitting the laser beam L1 into a plurality (K) of laser beams L2 without wavelength modulation. The splitter 12 is capable of splitting the laser beam L1 to generate a plurality (K) of laser beams L2. The laser beams L2 correspond to a specific example of the "optical signal" according to one embodiment of the present disclosure. The splitter 12 is configured, for example, by an optical coupler. The splitter 12 is configured, for example, by an SOI waveguide on a silicon substrate.

[0015] The optical circuit 10 further includes, for example, as shown in FIG. 2, a modulation circuit 13 and an amplification circuit 14. The modulation circuit 13 includes, for example, as shown in FIG. 1, a plurality (K number) of modulation circuits 13 （ｋ） (1≦k≦K). In this specification, the plurality (K number) of modulation circuits 13 （ｋ） refers to the modulation circuits 13 （１） ...13 （ｋ） ...13 （Ｋ） . The amplification circuit 14 includes, for example, as shown in FIG. 1, a plurality (K number) of amplification circuits 14 （ｋ） . In this specification, the plurality (K number) of amplification circuits 14 （ｋ） refers to the amplification circuits 14 （１） ...14 （ｋ） ...14 （Ｋ） . A circuit including the modulation circuit 13 and the amplification circuit 14 corresponds to a specific example of the "code multiplexing circuit" according to one embodiment of the present disclosure.

[0016] The modulation circuit 13 is capable of modulating each of a plurality (K number) of incident laser beams L2 with a different code sequence c for each laser beam L2 by using a plurality (K number) of mutually different code sequences c （ｋ） In this specification, the plurality (K number) of code sequences c （ｋ） refers to the code sequences c （ｋ） ...c （１） ...c （ｋ） ...c （Ｋ） . The modulation circuit 13 can output a plurality (K number) of laser beams L3 obtained by modulation （ｋ） to the amplification circuit 14. The code sequence c （ｋ） is represented by a vector (c １ （ｋ） ...c ｎ （ｋ） ...c Ｎ （ｋ） ) Ｔ (1≦n≦N). Here, T is the transpose of the vector. Hereinafter, the symbol length of each symbol included in the code sequence c （ｋ） is represented as T ｃ . The plurality of code sequences c （ｋ） are input from a generation circuit 22 described later to the modulation circuit 13. The plurality (K number) of laser beams L2 are input from a splitter 12 to the modulation circuit 13. Each modulation circuit 13 （ｋ）One of the multiple (K) laser beams L2 obtained by the splitter 12 is incident on it. In other words, the laser beam L1 is incident on the multiple (K) modulation circuits 13 by the splitter 12. （ｋ） It is distributed to each modulation circuit 13. （ｋ） The laser light L2 is transmitted via code sequence c （ｋ） By modulating with, the laser light L3 （ｋ） It is possible to generate each modulation circuit 13 （ｋ） The generated laser light L3 （ｋ） Amplification circuit 14 （ｋ） It can be output to [this format].

[0017] Each modulation circuit 13 （ｋ） This is composed, for example, by a Mach-Zehnder interferometer. Each modulation circuit 13 （ｋ） For example, as shown in Figure 3, the system is composed of waveguides P1 and P2 through which the laser beam L2 can propagate, and a pair of electrodes E1 and E2 that sandwich waveguide P2. One end of waveguides P1 and P2 is connected to each other, and the other ends of waveguides P1 and P2 are connected to each other. Laser beam L2 is incident from one end of waveguides P1 and P2, and the laser beam that has propagated through waveguides P1 and P2 interferes with each other at the other ends of waveguides P1 and P2. Due to the interference at the other ends of waveguides P1 and P2, the laser beam L3 （ｋ） Waveguides P1 and P2 are formed, for example, by SOI waveguides on a silicon substrate.

[0018] Electrode E1 has code sequence c （ｋ） A voltage train corresponding to the voltage is applied. The voltage train consists of, for example, K voltage signals that are continuous in time. A fixed voltage (e.g., 0V) is applied to electrode E2. In waveguide P1, the voltage applied by electrodes E1 and E2 modulates the phase of the laser light L2 propagating through waveguide P1 to 0 (rad) or π (rad). Therefore, the laser light L3 （ｋ） The code sequence c is relative to the laser light L2. （ｋ） This is obtained by the interference between the phase-modulated laser light corresponding to and the unmodulated laser light L2 that propagates through the waveguide P2.

[0019] Each modulation circuit 13 （ｋ）For example, it may be composed of a modulation circuit that operates on a different principle than phase modulation. Each modulation circuit 13 （ｋ） This may be configured, for example, by on-off keying.

[0020] The amplification circuit 14 uses multiple (K) laser beams L3 （ｋ） These can be amplified independently of each other. In this specification, a plurality of (K) laser beams L3 （ｋ） This refers to laser light L3 （１） ...L3 （ｋ） ...L3 （Ｋ） This refers to the amplification circuit 14 which emits multiple (K) laser beams L3 （ｋ） Multiple (K) setting values ​​z （ｋ） Using laser light L3 （ｋ） Different setting values ​​z （ｋ） It can be amplified by setting value z. （ｋ） is a vector (z １ （ｋ） ...z ｎ （ｋ） ...z Ｎ （ｋ） ) Ｔ It is expressed as (1 ≤ n ≤ N). In this specification, multiple (K) set values ​​z （ｋ） This refers to the set value z （１） ...z （ｋ） ...z （Ｋ） This refers to multiple setting values ​​z. （ｋ） This involves multiple (K) amplification circuits 14 from the control circuit 26 described later. （ｋ） It is input to each amplification circuit 14. （ｋ） This is the laser light L3 （ｋ） Set value z （ｋ） By amplifying it, the laser light L4 （ｋ） It is possible to generate laser light L4. （ｋ） This corresponds to a specific example of the "first modulated optical signal" according to one embodiment of the present disclosure. Each amplification circuit 14 （ｋ） The generated laser light L4 （ｋ） The transmitting and receiving circuit 15 described later （ｋ） Output is possible. Each amplification circuit 14 （ｋ） This is comprised of, for example, a semiconductor optical amplifier or an optical attenuator. Each amplification circuit 14 （ｋ）is configured to include, for example, an SOI waveguide on a silicon substrate.

[0021] The optical circuit 10 further includes a transmission / reception circuit 15, for example, as shown in FIG. 2. The transmission / reception circuit 15 includes a plurality (K pieces) of transmission / reception circuits 15 （ｋ） . In the present specification, the plurality (K pieces) of transmission / reception circuits 15 （ｋ） refers to the transmission / reception circuits 15 （１） …15 （ｋ） …15 （Ｋ） . Each transmission / reception circuit 15 （ｋ） includes, for example, as shown in FIG. 4, a transmission circuit 151 （ｋ） and a reception circuit 152 （ｋ） .

[0022] The transmission circuit 151 （ｋ） and the reception circuit 152 （ｋ） are each configured by, for example, a grating coupler. The grating coupler is configured to include, for example, a diffraction grating provided in an SOI waveguide on a silicon substrate. The transmission circuit 151 （ｋ） , when a laser beam L4 （ｋ） is input thereto, can transmit the input laser beam L4 （ｋ） to an external space. The laser beam transmitted to the external space by the transmission circuit 151 （ｋ） is referred to as a laser beam Lt （ｋ） . The laser beam Lt （ｋ） corresponds to a specific example of the "first modulated optical signal" according to an embodiment of the present disclosure. The plurality (K pieces) of transmission circuits 151 （ｋ） can transmit a plurality (K pieces) of laser beams Lt （ｋ） . In the present specification, the plurality (K pieces) of transmission circuits 151 （ｋ） refers to the transmission circuits 151 （１） …151 （ｋ） …151 （Ｋ） . In the present specification, the plurality (K pieces) of laser beams Lt （ｋ） refers to the laser beams Lt （１） …Lt （ｋ） …Lt （Ｋ） .

[0023] The laser beam Lt （ｋ）For example, it can be reflected by the target TG. Laser light Lt （ｋ） Of these, the light reflected by the target TG is the laser light Lr （ｋ） The receiving circuit 152 （ｋ） It can be directed towards. Laser light Lr （ｋ） This corresponds to a specific example of the "reflected light signal" according to one embodiment of the present disclosure. Receiving circuit 152 （ｋ） is the transmission circuit 151 （ｋ） Laser light L4 （ｋ） In response to the transmission to the external space, laser light Lr （ｋ） It is possible to receive. Receiving circuit 152 （ｋ） The received laser light Lr （ｋ） Laser light L5 （ｋ） It can be output to the addition circuit 16 described later. Laser light L5 （ｋ） This corresponds to a specific example of the "reflected light signal" according to one embodiment of the present disclosure. Multiple (K) receiving circuits 152 （ｋ） This consists of multiple (K) transmitting circuits 151 （ｋ） Multiple (K) laser beams Lt （ｋ） In response to the transmission to the external space, multiple (K) laser beams Lr （ｋ） It is possible to receive. In this specification, a plurality (K) of receiving circuits 152 （ｋ） This refers to the receiving circuit 152 （１） ...152 （ｋ） ...152 （Ｋ） This refers to a plurality (K) of laser beams Lr （ｋ） This refers to laser light Lr （１） ...Lr （ｋ） ...Lr （Ｋ） It refers to.

[0024] Figure 5 shows multiple (K) laser beams Lt （ｋ） And multiple (K) laser beams Lr （ｋ） This illustrates an example of the relationship between the laser light Lt. （ｋ） For example, as shown in Figure 5, the code sequence c （ｋ） (c １ （ｋ） ...c ｎ （ｋ） ...c Ｎ （ｋ）It is light modulated by ). Laser light Lt （ｋ） Lt １ （ｋ） ...Lt ｎ （ｋ） ...Lt Ｎ （ｋ） It is represented by the laser light Lt. １ （ｋ） is the code c １ （ｋ） It is light modulated by laser light Lt ｎ （ｋ） is the code c ｎ （ｋ） It is light modulated by laser light Lt Ｎ （ｋ） is the code c Ｎ （ｋ） It is light modulated by laser light Lr （ｋ） For example, as shown in Figure 5, the code sequence c （ｋ） (c １ （ｋ） ...c ｎ （ｋ） ...c Ｎ （ｋ） ) Modulated laser light Lt （ｋ） This is light obtained from the laser light Lr. （ｋ） Lr １ （ｋ） ...Lr ｎ （ｋ） ...Lr Ｎ （ｋ） It is represented by the laser light Lr. １ （ｋ） is the code c １ （ｋ） It is light modulated by laser light Lr ｎ （ｋ） is the code c ｎ （ｋ） It is light modulated by laser light Lr Ｎ （ｋ） is the code c Ｎ （ｋ） It is light modulated by [a certain factor].

[0025] Multiple (K) laser beams Lt （ｋ） Each transmitting and receiving circuit 15 （ｋ） From time t ０ It is transmitted simultaneously. However, multiple (K) laser beams Lr（ｋ） Each transmitting and receiving circuit 15 （ｋ） They do not arrive simultaneously, but at different times. (Laser light Lr) （１） For example, time t ０ propagation delay time τ １ After the time has elapsed, the transmitting and receiving circuit 15 （Ｋ） It reaches. Laser light Lr （ｋ） For example, time t ０ propagation delay time τ ｋ After the time has elapsed, the transmitting and receiving circuit 15 （Ｋ） It reaches. Laser light Lr （Ｋ） For example, time t ０ propagation delay time τ Ｋ After the time has elapsed, the transmitting and receiving circuit 15 （Ｋ） It is shown that it is possible to reach this point.

[0026] Figure 6 shows multiple (K) laser beams Lr （ｋ） And multiple (K) laser beams L5 （ｋ） This illustrates an example of the relationship. In this specification, multiple (K) laser beams L5 （ｋ） This refers to laser light L5 （１） ...L5 （ｋ） ...L5 （Ｋ） This refers to the laser beam L5. Figure 6 shows the laser beam L5 （ｋ） However, the code sequence c （ｋ） (c １ （ｋ） ...c ｎ （ｋ） ...c Ｎ （ｋ） ) Modulated laser light Lt （ｋ） It is shown that the light was obtained from. Multiple (K) receiving circuits 152 （ｋ） This is a combination of multiple (K) laser beams Lr （ｋ） Upon receiving the signal, the multiple (K) laser beams Lr （ｋ） Multiple (K) laser beams L5 （ｋ） It can be output as follows: Multiple (K) receiving circuits 152 （ｋ） This is a multiple (K) laser beam L5 （ｋ） This can be output, for example, to an SOI waveguide on a silicon substrate.

[0027] The optical circuit 10 further includes an adder circuit 16, as shown in Figures 1 and 2. The adder circuit 16 uses a plurality (K) of laser beams L5 （ｋ） These can be added together to generate laser light L6. The laser light L6 corresponds to a specific example of the "added optical signal" according to one embodiment of the present disclosure. The adding circuit 16 is composed of, for example, an optical coupler. The adding circuit 16 is composed of, for example, an SOI waveguide on a silicon substrate.

[0028] The optical circuit 10 further includes a detection circuit 17, as shown in Figures 1 and 2. The detection circuit 17 is capable of converting laser light L6 into an electrical signal. The detection circuit 17 is configured to include, for example, a photodiode, and when laser light L6 is input to the light-receiving surface of the photodiode, the input laser light L6 can be converted into an electrical signal by the photodiode. The detection circuit 17 can output the electrical signal obtained by the conversion to the AD converter 23, which will be described later. The detection circuit 17 is configured to include, for example, a waveguide P3 through which laser light L6 can propagate, and a photodiode 17A coupled to the waveguide P3, as shown in Figure 7. The waveguide P3 is configured, for example, by an SOI waveguide on a silicon substrate. The photodiode 17A can detect the laser light L6 that has propagated through the waveguide P3. The detection circuit 17 can output the analog electrical signal Va obtained by detecting the laser light L6 in the photodiode 17A to the AD converter 23.

[0029] Next, the electrical circuit 20 will be described. The electrical circuit 20 includes, for example, a memory circuit 21, a generation circuit 22, an AD converter 23, a correlation circuit 24, a power ratio calculation circuit 25, and a control circuit 26, as shown in Figure 2. The circuit including the power ratio calculation circuit 25 and the control circuit 26 corresponds to one specific example of the "control circuit" according to one embodiment of the present disclosure. The correlation circuit 24, the power ratio calculation circuit 25, and the control circuit 26 are each configured to include, for example, a processor. The correlation circuit 24 is, for example, a plurality (K) of correlation circuits 24, as shown in Figure 1. （ｋ） It has a plurality (K) correlation circuit 24 （ｋ） This refers to the correlation circuit 24 （１） ...24（ｋ） ...24 （Ｋ） This refers to the power ratio calculation circuit 25, for example, as shown in Figure 1, which consists of multiple (K) power ratio calculation circuits 25. （ｋ） It has a plurality (K) of power ratio calculation circuits 25 （ｋ） This refers to the power ratio calculation circuit 25 （１） ...25 （ｋ） ...25 （Ｋ） This refers to the electrical circuit 20, for example, as shown in Figure 2, which may optionally include a driver 27 capable of driving the laser light source 11.

[0030] The memory circuit 21 stores multiple (K) code sequences c of a predetermined code sequence length. （ｋ） Store the following: code sequence c （ｋ） This is, for example, a pseudorandom sequence, an Hadamard code, or a sequence of codes obtained by multiplying a pseudorandom sequence and an Hadamard code together. Multiple (K) sequence of codes c （ｋ） This is called a set of code sequences ST. In the code sequence group ST, each code sequence c （ｋ） The code sequence lengths are equal to each other. The memory circuit 21 further stores multiple sets (M sets) of code sequence groups ST having different code sequence lengths. The memory circuit 21 is composed of, for example, non-volatile memory. The memory circuit 21 is composed of, for example, EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory, resistive random-access memory, etc.

[0031] The generation circuit 22 receives a single code sequence group ST (multiple (K) code sequences c) from the memory circuit 21. （ｋ） The generation circuit 22 can read out the code sequence group ST (multiple (K) code sequences c) read from the memory circuit 21. （ｋ） Multiple (K) modulation circuits 13 （ｋ） It can output to the code sequence c. The generation circuit 22 generates the code sequence c. （ｋ） Modulation circuit 13 （ｋ） It can be output to [this format].

[0032] The AD converter 23 can convert the analog electrical signal Va input from the detection circuit 17 into a digital electrical signal Vd. The AD converter 23 can sample the electrical signal Va at a predetermined sampling period. The sampling period of the AD converter 23 is determined by the code sequence c （ｋ） Symbol length T ｃ Same as or shorter than this, for example, T ｃ The expression is / X (where X is a positive integer). The AD converter 23 uses multiple (K) correlation circuits 24 to convert the electrical signal Vd obtained by the conversion. （ｋ） It can be output to [this format].

[0033] The correlation circuit 24 connects the laser light L6 with a sequence of multiple (K) code elements c. （ｋ） Correlation with the code sequence c （ｋ） Calculate each one, and thereafter obtain multiple (K) correlation signals α （ｋ） | c （ｋ） | ２ It is possible to generate multiple (K) correlation signals α （ｋ） | c （ｋ） | ２ This refers to the correlation signal α （１） | c （１） | ２ …α （ｋ） | c （ｋ） | ２ …αx （Ｋ） | c （Ｋ） | ２ This refers to the correlation circuit 24, which generates multiple (K) correlation signals α （ｋ） | c （ｋ） | ２ Multiple (K) electrical signals V ｏｕｔ （ｋ） It can be output as follows. In this specification, multiple (K) electrical signals V ｏｕｔ （ｋ） This refers to the electrical signal V ｏｕｔ （１） ...V ｏｕｔ （ｋ） ...V ｏｕｔ （Ｋ） This refers to each correlation circuit 24. （ｋ） This is the laser light L6 and the code sequence c （ｋ） The correlation with is calculated, and the correlation signal α is obtained from this. （ｋ） | c （ｋ） | ２It is possible to generate the following. The correlation circuit 24 uses the electrical signal Vd obtained from the laser light L6 and a sequence of multiple (K) code elements c （ｋ） Correlation with the code sequence c （ｋ） Calculate each one, and thereafter obtain multiple (K) correlation signals α （ｋ） | c （ｋ） | ２ Each correlation circuit 24 can generate. （ｋ） This is the electrical signal Vd and code sequence c obtained from the laser beam L6. （ｋ） The correlation with is calculated, and the correlation signal α is obtained from this. （ｋ） | c （ｋ） | ２ It is possible to generate this.

[0034] Figure 8 shows the correlation circuit 24 （ｋ） This shows an example of the circuit configuration. In Figure 8, the analog electrical signal Va is represented by the code sequence c （ｋ） (c １ （ｋ） ...c ｎ （ｋ） ...c Ｎ （ｋ） It is shown that the signal is obtained from the laser light L6 modulated by ). The analog electrical signal Va is, for example, as shown in Figure 8, Va １ （ｋ） ...Va ｎ （ｋ） ...Va Ｎ （ｋ） Each correlation circuit 24 （ｋ） For example, as shown in Figure 8, register 24A （ｋ） And, register 24B （ｋ） And, multiplication circuit 24C （ｋ） And, the adding circuit 24D （ｋ） It has the following characteristics.

[0035] Register 24A （ｋ） Register 24A can store the electrical signal Vd output from the AD converter 23. （ｋ） Register 24A can sequentially store the b-bit word-length quantized electrical signal Vd output from the AD converter 23, one word at a time. （ｋ） It can store N x X words of data, where N is the code sequence c. （ｋ） The code c included ｎ（ｋ） This is the number. Here, let's assume X is 2. At this time, register 24A （ｋ） It can store 2N words of data. Register 24B （ｋ） is the code sequence c （ｋ） (c １ （ｋ） ...c ｎ （ｋ） ...c Ｎ （ｋ） ) Remember this.

[0036] Multiplication circuit 24C （ｋ） This is register 24A （ｋ） From there, for each sample period of the AD converter 23, N words of data (D １ （ｋ） ...D ｎ （ｋ） ...D Ｎ （ｋ） It is possible to read ) here. １ （ｋ） In the analog electrical signal Va, the code c １ （ｋ） Modulated data Va １ （ｋ） This is digital data. ｎ （ｋ） In the analog electrical signal Va, the code c ｎ （ｋ） Modulated data Va ｎ （ｋ） This is digital data. Ｎ （ｋ） In the analog electrical signal Va, the code c Ｎ （ｋ） Modulated data Va Ｎ （ｋ） It is digital data.

[0037] Multiplication circuit 24C （ｋ） This is register 24A （ｋ） From the N x X word data stored, data is extracted at X word intervals, thereby generating N word data (D １ （ｋ） ...D ｎ （ｋ） ...D Ｎ （ｋ）) can be generated. Register 24A （ｋ） The order of the N words of data obtained changes with each sample period of the AD converter 23. Register 24A （ｋ） The N-word data obtained changes in order as time progresses with each sample cycle of the AD converter 23, for example, as shown in Figure 9.

[0038] For example, at time ta, register 24A （ｋ） The N-word data obtained from D Ｎ－１ （ｋ） D Ｎ （ｋ） ...D ｎ－２ （ｋ） ...D Ｎ－２ （ｋ） For example, at time tb, register 24A （ｋ） The N-word data obtained from D Ｎ （ｋ） D １ （ｋ） ...D ｎ－１ （ｋ） ...D Ｎ－１ （ｋ） For example, at time tc, register 24A （ｋ） The N-word data obtained from D １ （ｋ） D ２ （ｋ） ...D ｎ （ｋ） ...D Ｎ （ｋ） For example, at time td, register 24A （ｋ） The N-word data obtained from D ２ （ｋ） D ３ （ｋ） ...D ｎ＋１ （ｋ） ...D １ （ｋ） That's how it is.

[0039] Multiplication circuit 24C （ｋ） This is register 24B （ｋ） From there, for each sample period of the AD converter 23, N words of data c １ （ｋ） ...c ｎ（ｋ） ...c Ｎ （ｋ） It is possible to read this. Multiplication circuit 24C （ｋ） This is register 24A （ｋ） The N-word data obtained from and register 24B （ｋ） The N words of data obtained from are multiplied by common digits, and the resulting N words are added to the adder circuit 24D （ｋ） Output is possible. Adding circuit 24D （ｋ） This is the multiplication circuit 24C （ｋ） The N words obtained are added together, and the resulting electrical signal V is obtained. ｏｕｔ （ｋ） (=α （ｋ） | c （ｋ） | ２ It is possible to output ).

[0040] The following is register 24A （ｋ） The N-word data obtained from this is called data D. Register 24B （ｋ） The N-word data obtained from this is called data C. When the correlation between data D and data C is large, the correlation circuit 24 （ｋ） The output will be maximized. A large correlation between data D and data C means, specifically, that the modulation factor (code c) in data D is large. ｎ （ｋ） The order of the elements is the code c of data C. ｎ （ｋ） This refers to matching the order of the data. When the correlation between data D and data C is small, the correlation circuit 24 （ｋ） The output will be minimized. A small correlation between data D and data C means that, specifically, the modulation factor (code c) in data D is small. ｎ （ｋ） The order of the elements is the code c of data C. ｎ （ｋ） This refers to a discrepancy in the order of the elements. (Adding circuit 24D) （ｋ） The output is maximized at time tc, for example, when the correlation between data D and data C is high, as shown in Figure 10.

[0041] Figure 11 shows an example of the output of a correlation circuit 24 in a K-channel type optical multiplexing circuit 1 from which K laser beams L2 are emitted. As shown in Figure 11, the K outputs of the correlation circuit 24 obtained based on the K laser beams L2 are determined by the propagation delay time τ １ , …, τ ｋ , …, τ Ｋ It reaches its maximum at the appropriate timing.

[0042] The power ratio calculation circuit 25 is connected to each correlation circuit 24 （ｋ） At the output, the correlation circuit 24 （ｋ） By calculating the ratio of the peak intensity and floor intensity of the output of each correlation circuit 24 （ｋ） It is possible to obtain the signal power to interference power ratio SIR. Each power ratio calculation circuit 25 （ｋ） This is the correlation circuit 24 （ｋ） By calculating the ratio of the peak intensity and floor intensity of the output, the correlation circuit 24 （ｋ） It is possible to obtain the signal power to interference power ratio SIR. Each power ratio calculation circuit 25 （ｋ） The obtained signal power versus interference power ratio (SIR) can be output to the control circuit 26.

[0043] The control circuit 26 controls each correlation circuit 24 （ｋ） The modulation circuit 13 can be controlled so that the signal power to interference power ratio (SIR) of the outputs are approximately the same. Here, multiple (K) correlation circuits 24 （ｋ） Desired correlation circuit 24 in the output （ｋ） Assume that the signal power to interference power ratio (SIR) of a specific signal, which is the output of the control circuit, is smaller than the target value. In this case, the control circuit 26 generates multiple (K) amplification circuits 14 to increase the signal power to interference power ratio (SIR) of the specific signal. （ｋ） It is possible to control this. Assume that the signal power to interference power ratio SIR of a specific signal is greater than the target value. In this case, the control circuit 26 uses multiple (K) amplification circuits 14 to reduce the signal power to interference power ratio SIR of the specific signal. （ｋ） It is controllable.

[0044] The control circuit 26 controls each correlation circuit 24 （ｋ） Multiple setting values ​​z are used so that the signal power to interference power ratio (SIR) of the output is approximately the same for each other.（ｋ） It is possible to set multiple setting values ​​z. （ｋ） The signal power to interference power ratio SIR of a specific signal is output to the amplification circuit 14. The control circuit 26, when the signal power to interference power ratio SIR of a specific signal is smaller than the target value, sets the set value z corresponding to the specific signal. （ｋ） It is possible to reset this to a value obtained by adding a certain value (+Δz) to the value set previously. The control circuit 26, when the signal power to interference power ratio SIR of a specific signal is greater than the target value, sets the set value z corresponding to the specific signal. （ｋ） It is possible to reset this value to the value obtained by subtracting a certain value (Δz) from the value set last time.

[0045] When the signal power to interference power ratio (SIR) of a specific signal is smaller than the target value, the control circuit 26 generates a plurality of code sequences c （ｋ） The generation circuit 22 can be controlled to increase the code sequence length. The generation circuit 22, in accordance with the control from the control circuit 26 (request for code sequence length extension), selects from among multiple code sequence groups ST that are included in the code sequence group ST with a longer code sequence length, and generates multiple code sequences c （ｋ） It is possible to read the data from the memory circuit 21 and supply it to the modulation circuit 13. When the signal power to interference power ratio SIR of a specific signal is greater than the target value, the control circuit 26 generates a plurality of code sequences c （ｋ） The generation circuit 22 can be controlled to shorten the code sequence length. The generation circuit 22, in accordance with the control from the control circuit 26 (request for shortening the code sequence length), selects from among multiple code sequence groups ST that are included in the code sequence group ST with the shorter code sequence length, and generates multiple code sequences c （ｋ） It is possible to read the data from the memory circuit 21 and supply it to the modulation circuit 13.

[0046] Figure 12 illustrates the signal power before and after correlation processing in Comparative Example A. Figure 13 illustrates the signal power before and after correlation processing in Comparative Example B. Figure 14 illustrates the signal power before and after correlation processing in this embodiment. In Figures 12 to 14, the electrical signal Vd （１） This is the code sequence c contained in the electrical signal Vd.（１） This is an electrical signal modulated by Vd. （２） This is the code sequence c contained in the electrical signal Vd. （２） This is an electrical signal modulated by Vd. （３） This is the code sequence c contained in the electrical signal Vd. （３） This is an electrical signal modulated by [the specified modulus]. And in this example, the electrical signal Vd （３） This will be the desired signal.

[0047] In Comparative Example A, as shown in Figure 12, the three electrical signals Vd in the correlation circuit 24 before correlation processing （１） , Vd （２） , Vd （３） The powers of the two are equal. At this time, in the correlation circuit 24, the code sequence c （３） and three electrical signals Vd （１） , Vd （２） , Vd （３） The correlation with is calculated. Then, the three electrical signals V after correlation processing are ｏｕｔ （１） , V ｏｕｔ （２） , V ｏｕｔ （３） In this case, the electrical signal V ｏｕｔ （３） The power of the electrical signal Vd before correlation processing （３） It becomes N times the value of the electrical signal V. ｏｕｔ （３） The SIR is N, as shown in Figure 12. Electrical signal V ｏｕｔ （３） When the SIR exceeds 1, the electrical signal V is generated from the output of the correlation circuit 24. ｏｕｔ （３） It can be detected.

[0048] In Comparative Example B, as shown in Figure 13, before the correlation processing in the correlation circuit 24, the electrical signal Vd （１） The power of the electrical signal Vd （２） , Vd （３） It is several times greater than the total power. At this time, in the correlation circuit 24, the code sequence c （３） and three electrical signals Vd （１） , Vd （２） , Vd （３）The correlation with is calculated. Then, the three electrical signals V after correlation processing are ｏｕｔ （１） , V ｏｕｔ （２） , V ｏｕｔ （３） In this case, the electrical signal V ｏｕｔ （３） The power of the electrical signal V ｏｕｔ （１） , V ｏｕｔ （２） The total power becomes smaller than the sum of the powers. At this time, the electrical signal V ｏｕｔ （３） The SIR is less than 1, as shown in Figure 13. Therefore, the electrical signal V ｏｕｔ （３） This is an electrical signal V ｏｕｔ （１） , V ｏｕｔ （２） It gets buried, and the electrical signal V from the output of the correlation circuit 24 ｏｕｔ （３） It cannot be detected.

[0049] In this embodiment, before the correlation processing in the correlation circuit 24, the electrical signal Vd （１） The power of the electrical signal Vd （２） , Vd （３） When the total power is several times greater than the electrical signal Vd （１） The power of the electrical signal Vd （２） , Vd （３） The amplification circuit 14 is controlled so that the SIR of each of the signals is approximately the same. As a result, for example, as shown in Figure 14, the electrical signal Vd （１） , Vd （２） , Vd （３） The power of each element becomes equal to the other. Thus, the power of the electrical signal Vd is adjusted. （１） , Vd （２） , Vd （３） and the code sequence c （３） The correlation between these is calculated in the correlation circuit 24. Then, the three electrical signals V after correlation processing are obtained. ｏｕｔ （１） , V ｏｕｔ （２） , V ｏｕｔ （３） In this case, the electrical signal V ｏｕｔ（３） The power of the electrical signal Vd before correlation processing （３） It becomes N times the value of the electrical signal V. ｏｕｔ （３） The SIR is N, as shown in Figure 12. Electrical signal V ｏｕｔ （３） When the SIR exceeds 1, the electrical signal V is generated from the output of the correlation circuit 24. ｏｕｔ （３） It can be detected.

[0050] [Effects] Next, the effects of the optical multiplexing circuit 1 will be explained.

[0051] In this embodiment, multiple (K) laser beams L2 emit multiple (K) different code sequences c （ｋ） A different code sequence c is used for each laser beam L2. （ｋ） It is modulated, thereby producing multiple (K) laser beams L3 （ｋ） This is obtained. Multiple (K) laser beams L3 （ｋ） These are amplified independently by the amplification circuit 14, thereby producing multiple (K) laser beams L4 （ｋ） This is obtained. Multiple (K) laser beams L4 （ｋ） This is a combination of multiple (K) laser beams Lt （ｋ） As such, multiple (K) laser beams Lt are transmitted into the external space. （ｋ） In response to the transmission, multiple (K) laser beams Lr （ｋ） This is obtained. Multiple (K) laser beams Lr （ｋ） These are added together to obtain the laser beam L6. The laser beam L6 and code sequence c （ｋ） The correlation with is calculated, and the correlation signal α is then generated. （ｋ） | c （ｋ） | ２ Each correlation signal α is obtained. （ｋ） | c （ｋ） | ２ The amplification circuit 14 is controlled so that the signal power to interference power ratio (SIR) of the multiple (K) laser beams Lr （ｋ） The interference in this region can be adjusted. As a result, even when the target TG is located near the optical multiplexing circuit 1, interference due to strong reflected light from the target TG can be suppressed.

[0052] In this embodiment, each correlation circuit 24 （ｋ） At the output, the correlation circuit 24 （ｋ） By calculating the ratio of the peak intensity and floor intensity of the output of each correlation circuit 24 （ｋ） The signal power to interference power ratio SIR is obtained. This allows each correlation circuit 24 （ｋ） The amplification circuit 14 is controlled so that the signal power to interference power ratio (SIR) of the outputs is approximately the same for each other. As a result, multiple (K) laser beams Lr （ｋ） The interference in this context can be adjusted.

[0053] In this embodiment, when the signal power to interference power ratio SIR of a specific signal is smaller than the target value, the amplification circuit 14 is controlled so that the signal power to interference power ratio SIR of the specific signal becomes larger. As a result, each correlation circuit 24 （ｋ） The amplification circuit 14 is controlled so that the signal power to interference power ratio (SIR) of the outputs is approximately the same for each other. As a result, multiple (K) laser beams Lr （ｋ） The interference in this context can be adjusted.

[0054] In this embodiment, when the signal power to interference power ratio SIR of a specific signal is greater than the target value, the amplification circuit 14 is controlled so that the signal power to interference power ratio SIR of the specific signal becomes smaller. As a result, each correlation circuit 24 （ｋ） The amplification circuit 14 is controlled so that the signal power to interference power ratio (SIR) of the outputs is approximately the same for each other. As a result, multiple (K) laser beams Lr （ｋ） The interference in this context can be adjusted.

[0055] In this embodiment, when the signal power to interference power ratio (SIR) of a specific signal is smaller than the target value, multiple (K) code sequences c （ｋ） The generation circuit 22 is controlled so that the code sequence length of each correlation circuit 24 is increased. （ｋ） The generation circuit 22 is controlled so that the signal power to interference power ratio (SIR) of the outputs is approximately the same for each other. As a result, multiple (K) laser beams Lr （ｋ） Each correlation circuit 24 （ｋ）The signal power to interference power ratio (SIR) can be adjusted. Therefore, multiple (K) laser beams Lr （ｋ） The interference in this context can be adjusted.

[0056] In this embodiment, when the signal power to interference power ratio (SIR) of a specific signal is greater than the target value, multiple (K) code sequences c （ｋ） The generation circuit 22 is controlled so that the code sequence length of each correlation circuit 24 is shortened. （ｋ） The generation circuit 22 is controlled so that the signal power to interference power ratio (SIR) of the outputs is approximately the same for each other. As a result, multiple (K) laser beams Lr （ｋ） Each correlation circuit 24 （ｋ） The signal power to interference power ratio (SIR) can be adjusted. Therefore, multiple (K) laser beams Lr （ｋ） The interference in this context can be adjusted.

[0057] In this embodiment, when the signal power to interference power ratio (SIR) of a specific signal is smaller than the target value, multiple (K) code sequences c included in the code sequence group ST with a longer code sequence length are selected from among the multiple code sequence groups ST. （ｋ） This is read from the memory circuit 21 and supplied to the modulation circuit 13. This then enables each correlation circuit 24 （ｋ） The generation circuit 22 is controlled so that the signal power to interference power ratio (SIR) of the outputs is approximately the same for each other. As a result, multiple (K) laser beams Lr （ｋ） Each correlation circuit 24 （ｋ） The signal power to interference power ratio (SIR) can be adjusted. Therefore, multiple (K) laser beams Lr （ｋ） The interference in this context can be adjusted.

[0058] In this embodiment, when the signal power to interference power ratio (SIR) of a specific signal is greater than the target value, multiple (K) code sequences c included in the code sequence group ST with a shorter code sequence length are selected from among the multiple code sequence groups ST. （ｋ） This is read from the memory circuit 21 and supplied to the modulation circuit 13. This then enables each correlation circuit 24 （ｋ） The generation circuit 22 is controlled so that the signal power to interference power ratio (SIR) of the outputs is approximately the same for each other. As a result, multiple (K) laser beams Lr（ｋ） Each correlation circuit 24 （ｋ） The signal power to interference power ratio (SIR) can be adjusted. Therefore, multiple (K) laser beams Lr （ｋ） The interference in this context can be adjusted.

[0059] In this embodiment, multiple (K) laser beams Lt are simultaneously irradiated toward the target TG. （ｋ） Multiple (K) code sequences c used for modulation （ｋ） This uses a pseudorandom sequence, an Hadamard code, or a sequence of codes obtained by multiplying a pseudorandom sequence and an Hadamard code together. This results in multiple (K) sequences of codes c. （ｋ） Using this, multiple (K) laser beams Lr （ｋ） Each correlation circuit 24 （ｋ） The signal power to interference power ratio (SIR) can be adjusted. As a result, multiple (K) laser beams Lr （ｋ） The interference in this context can be adjusted.

[0060] In this embodiment, the electrical signal Vd obtained from the laser light L6 and a plurality (K) code sequence c （ｋ） The correlation with the code sequence c （ｋ） Each is calculated, thereby generating multiple (K) correlation signals α （ｋ） | c （ｋ） | ２ This generates multiple (K) code sequences c. （ｋ） Using this, multiple (K) laser beams Lr （ｋ） The signal power to interference power ratio (SIR) of each signal can be adjusted. As a result, multiple (K) laser beams Lr （ｋ） The interference in this context can be adjusted.

[0061] In this embodiment, a modulation circuit 13, an amplification circuit 14, a transmitting / receiving circuit 15, an adding circuit 16, and a detection circuit 17 are provided in the optical circuit 10. The detection circuit 17 includes a photodiode. The amplification circuit 14 includes a semiconductor optical amplifier or an optical attenuator. The transmitting / receiving circuit 15 includes a diffraction grating. On the other hand, a memory circuit 21, a generation circuit 22, an AD converter 23, a correlation circuit 24, a power ratio calculation circuit 25, and a control circuit 26 are provided in the electrical circuit 20. The correlation circuit 24, the power ratio calculation circuit 25, and the control circuit 26 each include a processor. Thus, in this embodiment, the optical multiplexing circuit 1 is divided into an optical circuit 10 and an electrical circuit 20. As a result, for example, the optical multiplexing circuit 1 can be realized by stacking a substrate 10A including the optical circuit 10 and a substrate 20A including the electrical circuit 20 on each other using hybrid bonding. Furthermore, the reliability of the wiring between the optical circuit 10 and the electrical circuit 20 can be improved.

[0062] <2. Second Embodiment> Next, the configuration of the optical multiplexing circuit 2 according to the second embodiment of the present disclosure will be described. In the following, descriptions of configurations and effects common to the first embodiment will be omitted as appropriate. Figure 15 shows an example of the functional block of the optical multiplexing circuit 2. Figure 16 shows an example of the cross-sectional structure of the optical multiplexing circuit 2. The optical multiplexing circuit 2 includes, for example, an optical circuit 30 and an electrical circuit 40, as shown in Figure 15.

[0063] The optical circuit 30 is provided within the substrate 30A, for example, as shown in Figure 16. The electrical circuit 40 is provided within the substrate 40A, for example, as shown in Figure 16. The substrates 30A and 40A are laminated together by so-called hybrid bonding, for example, as shown in Figure 16. Hybrid bonding refers to a strong intermolecular bond between the insulating film (e.g., silicon oxide) on the surface of the substrate 30A and the insulating film (e.g., silicon oxide) on the surface of the substrate 40A, and a metallic bond between multiple copper (Cu) pads on the surface of the substrate 30A and multiple Cu pads on the surface of the substrate 40A. The multiple Cu pads used in hybrid bonding constitute part of the wiring that electrically connects the optical circuit 30 and the electrical circuit 40.

[0064] The optical circuit 30 includes, for example, a laser light source 11, a splitter 12, an amplification circuit 14, a transmitting / receiving circuit 15, and an adding circuit 16, as shown in Figure 16. The optical circuit 30 corresponds to the optical circuit 10 in which the modulation circuit 13 is omitted.

[0065] The amplification circuit 14 can amplify multiple (K) laser beams L2 independently of each other. The amplification circuit 14 amplifies multiple (K) laser beams L2 to multiple (K) set values ​​z^ （ｋ） Using different setting values ​​z^ for each laser beam L2 （ｋ） It can be amplified by multiple (K) set values ​​z^ （ｋ） This refers to the setting value z^ （１） ...z^ （ｋ） ...z^ （Ｋ） This refers to the setting value z^ （ｋ） This is expressed by the equation shown in Figure 15. In the equation shown in Figure 15, z （ｋ） and c （ｋ） The symbol between indicates the Kronecker product. Multiple (K) setting values ​​z^ （ｋ） This involves multiple (K) amplification circuits 14 from the multiplication circuit 28 described later. （ｋ） It is input to each amplification circuit 14. （ｋ） The laser beam L2 is set to the value z^ （ｋ） By amplifying it, the laser light L4 （ｋ） It is possible to generate laser light L4. （ｋ）This corresponds to a specific example of the "first modulated optical signal" according to one embodiment of the present disclosure. Each amplification circuit 14 （ｋ） The generated laser light L4 （ｋ） transmit / receive circuit 15 （ｋ） It can be output to [this format].

[0066] The electrical circuit 40 includes, for example, a memory circuit 21, a generation circuit 22, an AD converter 23, a correlation circuit 24, a power ratio calculation circuit 25, a control circuit 26, and a multiplication circuit 28, as shown in Figure 16. The generation circuit 22 reads a group of code sequences ST (multiple (K) code sequences c) from the memory circuit 21. （ｋ） The multiplication circuit 28 can output a set value z. （ｋ） The multiplication circuit 28 can output this. In this specification, multiple (K) set values ​​z （ｋ） This refers to the set value z （１） ...z （ｋ） ...z （Ｋ） It refers to.

[0067] The multiplication circuit 28 receives multiple (K) code sequences c from the generation circuit 22. （ｋ） And multiple (K) set values ​​z obtained from the control circuit 26 （ｋ） Based on this, multiple (K) setting values ​​z^ （ｋ） It is possible to generate the following. The multiplication circuit 28 multiplies the generated set value z^ （ｋ） The output can be sent to the amplification circuit 14. The multiplication circuit 28 can be, for example, a plurality (K) of multiplication circuits 28 as shown in Figure 15. （ｋ） Each multiplication circuit 28 （ｋ） is the code sequence c （ｋ） and the set value z （ｋ） Multiply these two values ​​together, and thereby obtain the set value z （ｋ） It is possible to generate each multiplication circuit 28 （ｋ） The generated setting value z^ （ｋ） Amplification circuit 14 （ｋ） It can be output to [this format].

[0068] In this embodiment, multiple (K) laser beams L2 are used to control multiple set values ​​z^ （ｋ） Using different setting values ​​z^ for each laser beam L2 （ｋ） It is amplified by this. As a result, multiple (K) laser beams L4 （ｋ）This is obtained. Multiple (K) laser beams L4 （ｋ） This is a combination of multiple (K) laser beams Lt （ｋ） As such, multiple (K) laser beams Lt are transmitted into the external space. （ｋ） In response to the transmission, multiple (K) laser beams Lr （ｋ） This is obtained. Multiple (K) laser beams Lr （ｋ） These are added together to obtain the laser beam L6. The laser beam L6 and code sequence c （ｋ） The correlation with is calculated, and the correlation signal α is then generated. （ｋ） | c （ｋ） | ２ Each correlation signal α is obtained. （ｋ） | c （ｋ） | ２ The amplification circuit 14 is controlled so that the signal power to interference power ratio (SIR) of the multiple (K) laser beams Lr （ｋ） The interference in this region can be adjusted. As a result, even when the target TG is located near the optical multiplexing circuit 2, interference due to strong reflected light from the target TG can be suppressed.

[0069] <3. Third Embodiment> Next, the configuration of the distance measuring device 3 according to the third embodiment of the present disclosure will be described. In the following, descriptions of configurations and effects common to the first and second embodiments will be omitted as appropriate. Figure 17 shows an example of the functional block of the distance measuring device 3. The distance measuring device 3 includes, for example, optical multiplexing circuits 1 and 2 and a signal processing circuit 31, as shown in Figure 17. The signal processing circuit 31 processes multiple signals (multiple (K) electrical signals V) obtained by the optical multiplexing circuits 1 and 2. ｏｕｔ （ｋ） The position and distance of the target TG can be derived by signal processing using ).

[0070] In this embodiment, optical multiplexing circuits 1 and 2 output a plurality (K) of different code sequences c. （ｋ） Multiple (K) laser beams Lt modulated by （ｋ） The laser beams are transmitted towards the target TG. Furthermore, multiple (K) laser beams Lt are directed towards the target TG. （ｋ） In response to the transmission, multiple (K) laser beams Lr （ｋ）The following is received. This results in the electrical signal Va (electrical signal Vd) obtained from the detection circuit 17 and the code sequence c （ｋ） The correlation with is calculated, and the correlation signal α is then generated. （ｋ） | c （ｋ） | ２ (Electrical signal V) ｏｕｔ （ｋ） ) can be obtained. And each correlation signal α （ｋ） | c （ｋ） | ２ The amplification circuit 14 is controlled so that the signal power to interference power ratio SIR of the lasers is approximately the same for all of them. As a result, multiple (K) laser beams Lt that are simultaneously irradiated toward the target TG are controlled. （ｋ） The intensity of each of them can be adjusted. Alternatively, by controlling the generation circuit 22, multiple (K) laser beams Lr （ｋ） Each correlation circuit 24 （ｋ） The signal power to interference power ratio (SIR) can be adjusted. As a result, multiple (K) laser beams Lr （ｋ） Interference can be adjusted. Therefore, even when the target TG is located close to the rangefinder 3, interference due to strong reflected light from the target TG can be suppressed. As a result, high measurement accuracy can be obtained regardless of the distance to the target TG.

[0071] <4. Application Examples> The technology relating to this disclosure (this technology) can be applied to various products. For example, the technology relating to this disclosure may be implemented as a device mounted on any type of mobile vehicle such as an automobile, electric vehicle, hybrid electric vehicle, motorcycle, bicycle, personal mobility device, airplane, drone, ship, or robot.

[0072] Figure 18 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technology described herein may be applied.

[0073] The vehicle control system 12000 comprises a plurality of electronic control units connected via a communication network 12001. In the example shown in Figure 18, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. The functional configuration of the integrated control unit 12050 is shown in the figure, which includes a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface 12053.

[0074] The drivetrain control unit 12010 controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit 12010 functions as a control device for a drivetrain generating device that generates driving force for the vehicle, such as an internal combustion engine or a drive motor; a drivetrain transmission mechanism that transmits driving force to the wheels; a steering mechanism that adjusts the steering angle of the vehicle; and a braking device that generates braking force for the vehicle.

[0075] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window system, or various lamps such as headlights, reverse lights, brake lights, turn signals, or fog lights. In this case, the body system control unit 12020 may receive radio waves transmitted from a portable device that replaces a key or signals from various switches. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock system, power window system, lamps, etc.

[0076] The external information detection unit 12030 detects information from outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the external information detection unit 12030. The external information detection unit 12030 causes the imaging unit 12031 to capture images of the outside of the vehicle and receives the captured images. Based on the received images, the external information detection unit 12030 may perform object detection processing such as detecting people, cars, obstacles, signs, or characters on the road surface, or distance detection processing.

[0077] The imaging unit 12031 is a light sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0078] The in-vehicle information detection unit 12040 detects information inside the vehicle. The in-vehicle information detection unit 12040 is connected to, for example, a driver status detection unit 12041 that detects the driver's state. The driver status detection unit 12041 includes, for example, a camera that captures images of the driver, and the in-vehicle information detection unit 12040 may calculate the driver's level of fatigue or concentration, or determine whether the driver is drowsy, based on the detection information input from the driver status detection unit 12041.

[0079] The microcomputer 12051 can calculate control target values ​​for the drive force generator, steering mechanism, or braking device based on information inside and outside the vehicle acquired by the external information detection unit 12030 or the internal information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing ADAS (Advanced Driver Assistance System) functions, including collision avoidance or impact mitigation, following driving based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning.

[0080] Furthermore, the microcomputer 12051 can perform cooperative control for purposes such as autonomous driving, where the vehicle drives autonomously without driver intervention, by controlling the drive force generating device, steering mechanism, or braking device, etc., based on information about the vehicle's surroundings acquired by the external information detection unit 12030 or the internal information detection unit 12040.

[0081] Furthermore, the microcomputer 12051 can output control commands to the body system control unit 12020 based on external information acquired by the external information detection unit 12030. For example, the microcomputer 12051 can control the headlights according to the position of a preceding or oncoming vehicle detected by the external information detection unit 12030, and perform coordinated control aimed at reducing glare, such as switching from high beams to low beams.

[0082] The audio-image output unit 12052 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying information to the vehicle's occupants or to those outside the vehicle. In the example shown in Figure 18, the output devices include an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an onboard display and a head-up display.

[0083] Figure 19 shows an example of the installation position of the imaging unit 12031.

[0084] In Figure 19, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0085] The imaging units 12101, 12102, 12103, 12104, and 12105 are installed, for example, on the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle 12100. The imaging unit 12101 installed on the front nose and the imaging unit 12105 installed on the upper part of the windshield inside the vehicle mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 installed on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 installed on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 installed on the upper part of the windshield inside the vehicle is mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, or lanes.

[0086] Figure 19 shows an example of the imaging ranges of imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of imaging unit 12101 located on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of imaging units 12102 and 12103 located on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of imaging unit 12104 located on the rear bumper or back door. For example, by superimposing the image data captured by imaging units 12101 to 12104, an overhead view image of the vehicle 12100 can be obtained.

[0087] At least one of the imaging units 12101 to 12104 may have a function for acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera consisting of multiple image sensors, or an image sensor having pixels for phase difference detection.

[0088] For example, the microcomputer 12051, based on distance information obtained from the imaging units 12101 to 12104, can determine the distance to each object within the imaging range 12111 to 12114 and the temporal change of this distance (relative speed to the vehicle 12100). In particular, it can extract the closest object on the vehicle 12100's path that is traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or more) as the preceding vehicle. Furthermore, the microcomputer 12051 can set a predetermined distance to be maintained before the preceding vehicle and perform automatic braking control (including follow-and-stop control) and automatic acceleration control (including follow-and-start control), etc. In this way, cooperative control aimed at autonomous driving, where the vehicle drives autonomously without driver intervention, can be performed.

[0089] For example, the microcomputer 12051 can use distance information obtained from imaging units 12101 to 12104 to classify and extract three-dimensional object data related to three-dimensional objects, such as motorcycles, passenger cars, large vehicles, pedestrians, utility poles, and other three-dimensional objects, and use this data for automatic obstacle avoidance. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines the collision risk, which indicates the degree of risk of collision with each obstacle. If the collision risk is above a set value and there is a possibility of collision, the microcomputer 12051 can provide driving assistance to avoid collisions by outputting a warning to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or evasive steering via the drive system control unit 12010.

[0090] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared light. For example, the microcomputer 12051 can recognize pedestrians by determining whether or not pedestrians are present in the images captured by the imaging units 12101 to 12104. Such pedestrian recognition is performed, for example, by a procedure to extract feature points from the images captured by the imaging units 12101 to 12104 as infrared cameras, and a procedure to perform pattern matching on a series of feature points that indicate the contour of an object to determine whether or not it is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the imaging units 12101 to 12104 and recognizes a pedestrian, the audio-image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio-image output unit 12052 may also control the display unit 12062 to display an icon indicating a pedestrian at a desired position.

[0091] The above describes an example of a vehicle control system to which the technology described herein may be applied. The technology described herein can be applied to the imaging unit 12031, etc., among the configurations described above. By applying the technology described herein to the imaging unit 12031, etc., it is possible to accurately detect the position and distance of obstacles not only when they are far away from the vehicle 12100, but also when obstacles are located near the vehicle 12100. As a result, advanced vehicle control that takes into account the position and distance of obstacles around the vehicle 12100 can be realized.

[0092] Although this technology has been described above with reference to multiple embodiments and application examples, this technology is not limited to these embodiments, and various modifications are possible. Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also exist.

[0093] Furthermore, this technology can be configured as follows: (1) An optical multiplexing circuit comprising: a code multiplexing circuit capable of modulating each of a plurality of optical signals with a plurality of mutually different code sequences, each optical signal being independently amplified, thereby generating a plurality of first modulated optical signals; a transmitting and receiving circuit capable of transmitting the plurality of first modulated optical signals to an external space and receiving a plurality of reflected optical signals from the external space as a response to the transmission to the external space; an adding circuit capable of adding the plurality of reflected optical signals, thereby generating an added optical signal; a correlation circuit capable of calculating the correlation between the added optical signal and the plurality of code sequences for each code sequence, thereby generating a plurality of correlation signals; and a control circuit capable of controlling the code multiplexing circuit so that the signal power to interference power ratio of each of the correlation signals is approximately the same. (2) The optical multiplexing circuit according to (1), wherein the control circuit is capable of obtaining the signal power to interference power ratio of each correlation signal by calculating the ratio of the peak intensity and floor intensity of the correlation signal for each correlation signal. (3) The optical multiplexing circuit according to (1) or (1), wherein the control circuit is capable of controlling the code multiplexing circuit so that the signal power to interference power ratio of a specific signal, which is a desired correlation signal among the plurality of correlation signals, becomes larger when the signal power to interference power ratio of the specific signal is smaller than a target value. (4) The optical multiplexing circuit according to (3), wherein the control circuit is capable of controlling the code multiplexing circuit so that the signal power to interference power ratio of the specific signal becomes smaller when the signal power to interference power ratio of the specific signal is larger than a target value. (5) The optical multiplexing circuit according to (3), further comprising a generation circuit capable of generating the plurality of code sequences, wherein the control circuit is capable of controlling the generation circuit so that the code sequence length of the plurality of code sequences becomes longer when the signal power to interference power ratio of the specific signal is smaller than a target value.(6) The optical multiplexing circuit according to (4), further comprising a generation circuit capable of generating the plurality of code sequences, wherein the control circuit can control the generation circuit such that the code sequence length of the plurality of code sequences is shortened when the signal power to interference power ratio of the specific signal is greater than a target value. (7) The optical multiplexing circuit according to (3), further comprising a storage circuit for storing a plurality of code sequence groups having different code sequence lengths, wherein each code sequence group includes a plurality of code sequences having equal code sequence lengths, wherein the generation circuit can read out the plurality of code sequences included in the first code sequence group having a longer code sequence length from the storage circuit and supply it to the code multiplexing circuit when the signal power to interference power ratio of the specific signal is less than a target value. (8) The optical multiplexing circuit according to (4), further comprising a memory circuit for storing a plurality of groups of code sequences having different code sequence lengths, each of the plurality of code sequence groups including a plurality of code sequences having equal code sequence lengths, and the generation circuit is capable of reading out the plurality of code sequences included in a second code sequence group having a shorter code sequence length from the memory circuit and supplying it to the code multiplexing circuit when the signal power to interference power ratio of the specific signal is greater than a target value. (9) The optical multiplexing circuit according to any one of (1) to (8), wherein the code sequence is a pseudo-random sequence, an Hadamard code, or a code sequence obtained by multiplying a pseudo-random sequence and an Hadamard code together. (10) The optical multiplexing circuit according to any one of (1) to (9), further comprising a detection circuit capable of converting the summing optical signal into an electrical signal, wherein the correlation circuit is capable of calculating the correlation between the electrical signal and the plurality of code sequences for each code sequence, thereby generating the plurality of correlated signals. (11) The optical multiplexing circuit according to (10), wherein the circuit including the code multiplexing circuit, the transmitting and receiving circuit, the adding circuit and the detection circuit is composed of an optical circuit, and the circuit including the correlation circuit and the control circuit is composed of an electrical circuit. (12) The optical multiplexing circuit according to (11), wherein the detection circuit is composed of a photodiode.(13) The optical multiplexing circuit according to (11), wherein the correlation circuit and the control circuit each include a processor. (14) The optical multiplexing circuit according to any one of (11) to (13), wherein the code multiplexing circuit includes a modulation circuit capable of modulating each of a plurality of optical signals with a different code sequence for each optical signal using a plurality of mutually different code sequences, and an amplification circuit capable of amplifying a plurality of optically modulated signals obtained by the modulation circuit with a different setting value for each optically modulated signal using a plurality of mutually different setting values ​​obtained from the control circuit. (15) The optical multiplexing circuit according to (14), wherein the amplification circuit includes a semiconductor optical amplifier or an optical attenuator. (16) The optical multiplexing circuit according to any one of (11) to (15), wherein the transmitting and receiving circuit includes a diffraction grating. (17) The optical multiplexing circuit according to any one of (11) to (16), wherein the optical circuit and the electrical circuit are stacked on top of each other by hybrid bonding. (18) A distance measuring device comprising an optical multiplexing circuit as described in (1) to (17), and a signal processing circuit capable of deriving the position and distance of a target by signal processing using the signals obtained by the optical multiplexing circuit.

[0094] In this disclosure, multiple optical signals are modulated with different optical signals using different code sequences and amplified independently of each other to obtain multiple first modulated optical signals. The multiple first modulated optical signals are transmitted into the external space, and multiple reflected optical signals are received from the external space as a response to the transmission of the multiple first modulated optical signals. The multiple reflected optical signals are added together to generate an added optical signal. The correlation between the added optical signal and the multiple code sequences is calculated for each code sequence, thereby generating multiple correlation signals. The code multiplexing circuit is controlled so that the signal power to interference power ratio of each correlation signal is approximately the same. This makes it possible to adjust the signal power to interference power ratio of each of the multiple reflected optical signals obtained as a response to the multiple first modulated optical signals simultaneously irradiated toward the target. As a result, interference in the multiple reflected optical signals can be adjusted. Therefore, even when the target is located close to the optical multiplexing circuit, interference due to strong reflected light from the target can be suppressed. From the above, high measurement accuracy can be obtained regardless of the distance to the target.

[0095] This application claims priority based on U.S. Provisional Application No. 63 / 779810, filed with the U.S. Patent and Trademark Office on 28 March 2025, and all the contents of that application are incorporated herein by reference.

[0096] Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

1. An optical multiplexing circuit comprising: a code multiplexing circuit capable of modulating each of a plurality of optical signals with a plurality of different code sequences, each optical signal being independently amplified, thereby generating a plurality of first modulated optical signals; a transmitting and receiving circuit capable of transmitting the plurality of first modulated optical signals to an external space and receiving a plurality of reflected optical signals from the external space as a response to the transmission to the external space; an adding circuit capable of adding the plurality of reflected optical signals, thereby generating an added optical signal; a correlation circuit capable of calculating the correlation between the added optical signal and the plurality of code sequences for each code sequence, thereby generating a plurality of correlation signals; and a control circuit capable of controlling the code multiplexing circuit so that the signal power to interference power ratio of each of the correlation signals is approximately the same.

2. The optical multiplexing circuit according to claim 1, wherein the control circuit is capable of obtaining the signal power to interference power ratio of each correlation signal by calculating the ratio of the peak intensity to the floor intensity of each correlation signal.

3. The optical multiplexing circuit according to claim 1, wherein the control circuit is capable of controlling the code multiplexing circuit so that the signal power to interference power ratio of a specific signal, which is a desired correlation signal among the plurality of correlation signals, increases when the signal power to interference power ratio of the specific signal is smaller than a target value.

4. The optical multiplexing circuit according to claim 3, wherein the control circuit is capable of controlling the code multiplexing circuit so that the signal power to interference power ratio of the specific signal becomes smaller when the signal power to interference power ratio of the specific signal is larger than a target value.

5. The optical multiplexing circuit according to claim 3, further comprising a generation circuit capable of generating the plurality of code sequences, wherein the control circuit can control the generation circuit such that the code sequence length of the plurality of code sequences increases when the signal power to interference power ratio of the specific signal is smaller than the target value.

6. The optical multiplexing circuit according to claim 4, further comprising a generation circuit capable of generating the plurality of code sequences, wherein the control circuit can control the generation circuit such that the code sequence length of the plurality of code sequences is shortened when the signal power to interference power ratio of the specific signal is greater than a target value.

7. The optical multiplexing circuit according to claim 3, further comprising a memory circuit for storing a plurality of groups of code sequences having different code sequence lengths, each of the plurality of code sequence groups including a plurality of code sequences having equal code sequence lengths, and the generation circuit is capable of reading out the plurality of code sequences included in the first code sequence group having a longer code sequence length from the memory circuit 21 and supplying them to the code multiplexing circuit when the signal power to interference power ratio of the specific signal is smaller than the target value.

8. The optical multiplexing circuit according to claim 4, further comprising a memory circuit for storing a plurality of groups of code sequences having different code sequence lengths, each of the plurality of code sequence groups including a plurality of code sequences having equal code sequence lengths, and the generation circuit is capable of reading out the plurality of code sequences included in a second code sequence group having a shorter code sequence length from the memory circuit and supplying them to the code multiplexing circuit when the signal power to interference power ratio of the specific signal is greater than a target value.

9. The optical multiplexing circuit according to claim 1, wherein the code sequence is a pseudo-random sequence, an Hadamard code, or a code sequence obtained by multiplying a pseudo-random sequence and an Hadamard code together.

10. The optical multiplexing circuit according to claim 1, further comprising a detection circuit capable of converting the summing optical signal into an electrical signal, wherein the correlation circuit is capable of calculating the correlation between the electrical signal and the plurality of code sequences for each code sequence, thereby generating the plurality of correlated signals.

11. The optical multiplexing circuit according to claim 10, wherein the circuit including the code multiplexing circuit, the transmitting and receiving circuit, the adding circuit and the detection circuit is composed of an optical circuit, and the circuit including the correlation circuit and the control circuit is composed of an electrical circuit.

12. The optical multiplexing circuit according to claim 11, wherein the detection circuit includes a photodiode.

13. The optical multiplexing circuit according to claim 11, wherein the correlation circuit and the control circuit each include a processor.

14. The optical multiplexing circuit according to claim 11, wherein the code multiplexing circuit comprises a modulation circuit capable of modulating each of a plurality of optical signals with a different code sequence for each optical signal using a plurality of mutually different code sequences, and an amplification circuit capable of amplifying a plurality of optical modulated signals obtained by the modulation circuit with a different set value for each optical modulated signal using a plurality of mutually different set values ​​obtained from the control circuit.

15. The optical multiplexing circuit according to claim 14, wherein the amplification circuit comprises a semiconductor optical amplifier or an optical attenuator.

16. The optical multiplexing circuit according to claim 11, wherein the transmitting and receiving circuit is configured to include a diffraction grating.

17. The optical multiplexing circuit according to claim 11, wherein the optical circuit and the electrical circuit are stacked on top of each other by hybrid bonding.

18. A distance measuring device comprising an optical multiplexing circuit according to claims 1 to 17, and a signal processing circuit capable of deriving the position and distance of a target by signal processing using a plurality of signals obtained by the optical multiplexing circuit.

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