Optical communication system

Abstract

Parallel optical communication system technology has had a problem in which group delay time periods generally differ between wavelength channels and between spatial channels, and reception times of optical clock signals and optical main signals deviate from one another. An optical communication system according to the present invention is provided with a transmission device 100 for transmitting, through an optical transmission line 50, multiplexed signal light L mux obtained by subjecting an optical main signal Ssig, which has been modulated using transmission data on a signal multiplex axis 1, to clock modulation in which the optical main signal is further modulated by a clock signal Sclk on a signal multiplex axis 2 orthogonal to the signal multiplex axis 1. A reception device 200 acquires transmission data (main signal) by sampling the multiplexed signal light, which has propagated through the optical transmission line 50, on the basis of the modulation method of the clock modulation.

Description

Optical communication system

[0001] This disclosure relates to an optical communication system that transmits multiple optical signals in parallel.

[0002] With the development of artificial intelligence and machine learning technologies, the importance of image and video information acquired by cameras is increasing. Image recognition technology, which can accurately identify objects of interest from image and video data through image and video information processing, is attracting attention. This image recognition technology requires an image sensor 11 that receives light, an image signal processor 12 that generates an image, and an information processing base 13 based on the generated image (see Figure 1).

[0003] Image recognition technologies using artificial intelligence and machine learning require high-load signal processing and therefore consume a lot of power. For this reason, if an image signal processor or an information processing unit with a signal processing board is mounted on a camera, a robust power supply to the camera is necessary. However, power supply is a limiting factor in camera placement. Therefore, it is preferable to separate the image sensor and the information processing unit, allowing the sensor to be located at the shooting location and the information processing unit to be located in a remote location with abundant power. In the following explanation, "image signal processor" will be abbreviated as "image processor" or "processor."

[0004] For example, Non-Patent Document 1 discloses a camera that allows for the remote placement of an image sensor and an artificial intelligence-based signal processing board. Non-Patent Document 2 also discloses an interface that converts and transmits image sensor signals as Ethernet signals.

[0005] Nikon Product Introduction "Machine Vision Camera", https: / / digital-sol.nikon.com / products / cameras / (Accessed October 16, 2024) Thin Solutions Technology Overview V-by-one HS Technology, https: / / www.thinesollutions.com / v-by-one-hs-overview (Accessed September 26, 2024) "Demonstration of Timing Skew Compensation for Bit-Parallel WDM Data Transmission with PicoSecond Precision", S. Shen et al. , IEEE PHOTONICS TECHNOLOGY LETTERS, vol. 11, no. 5, pp. 566-568 (1999) “Comparing Inter-Core Skew Fluctuations in Multi-Core and Single-Core Fibers”, R. S. Luis et al. , CLEO SN2L. 5 (2015)

[0006] However, due to attenuation of electrical signal strength, the communication distance between the image sensor and the processor is limited to about 15 meters. Therefore, in order to expand the applicable range of camera installation locations, it is being considered to extend the communication distance by using low-loss optical communication between the image sensor and the processor.

[0007] Communication between the image sensor and the processor can use a format in which the clock signal and the main signal are transmitted in parallel. When the image sensor and the processor are connected by optical communication, the clock signal S ｃｌｋ and main signal S ｓｉｇ A method is envisioned in which the group delay time is assigned to the wavelength channel or spatial channel of the optical transmission path 50 and transmitted in parallel (see Figure 2). However, generally the group delay time differs between wavelength channels or spatial channels (see, for example, Non-Patent Documents 3 and 4). The difference in group delay time affects the optical clock signal L in the processor. ｃｌｋ and the main light signal L ｓｉｇThis causes signal skew, resulting in a delay in the reception time of the signals. The signal skew increases with increasing distance between the image sensor and the processor.

[0008] Due to this signal skew, extending the communication distance is difficult even when connecting the image sensor and processor with optical communication, which presents a challenge in expanding the applicable range of camera installation locations. Therefore, the present invention aims to provide an optical communication system that can improve signal skew in parallel transmission in order to solve the aforementioned problem.

[0009] To achieve the above objective, the optical communication system according to the present invention modulates the clock signal and the main signal on orthogonal signal multiplexing axes, multiplexes them, and transmits them in parallel.

[0010] Specifically, the optical communication system according to the present invention includes a transmitting device that transmits a clock-modulated multiplexed signal optical signal, which is obtained by further modulating an optical main signal modulated with transmission data on an arbitrary signal multiplexing axis with a clock signal on another signal multiplexing axis orthogonal to the aforementioned arbitrary signal multiplexing axis, over an optical transmission path.

[0011] The orthogonal signal multiplexing axes are, for example, intensity and polarization. As shown in Figure 3, the clock polarization modulator 55 receives the main signal S from the optical transmitter 54. ｓｉｇ The optical main signal L obtained by intensity modulation ｓｉｇ The clock signal S ｃｌｋ Polarization modulation is performed to rotate the polarization based on this, generating multiple signal light. This multiple signal light is one wavelength (for example, wavelength λ). １ The clock signal and the main signal are multiplexed in the optical transmission path 50, and no group delay difference occurs even when propagated through the optical transmission path 50.

[0012] Furthermore, the optical communication system according to the present invention further includes a receiving device that samples the multiplexed signal light propagated in the optical transmission path and acquires the transmission data based on the modulation scheme of the clock modulation.

[0013] Therefore, the present invention can provide an optical communication system that can improve signal skew in parallel transmission.

[0014] The transmitting device of the optical communication system according to the present invention is characterized in that, when there are multiple optical main signals, clock modulation is performed on each of the optical main signals on an additional signal multiplexing axis that is orthogonal to both the arbitrary signal multiplexing axis and the other signal multiplexing axes.

[0015] For example, if one signal multiplexing axis is intensity and another is polarization, then yet another signal multiplexing axis is wavelength. Multiple main signals are assigned to their respective wavelengths, and the aforementioned clock modulation is performed for each wavelength. When propagated through the optical transmission path 50, a delay occurs between the main signals due to group delay differences, but no group delay difference occurs between one main signal and its clock signal.

[0016] In this case, the optical communication system according to the present invention further comprises a receiving device that separates each of the optical main signals multiplexed on other signal multiplexing axes from the multiplexed signal light propagated in the optical transmission path, and samples each of the multiplexed signal light based on the modulation scheme of the clock modulation to acquire the transmission data.

[0017] Furthermore, the above inventions can be combined as much as possible.

[0018] The present invention can provide an optical communication system that can improve signal skew in parallel transmission. In other words, the present invention can extend the communication distance of an optical communication system that transmits multiple optical signals in parallel, improve the flexibility of the connection between the image sensor and the image processor, and expand the range of applicable camera installation locations.

[0019] This is a diagram illustrating the configuration of image recognition technology. This is a diagram illustrating the configuration of image recognition technology including optical communication. This is a diagram illustrating the optical communication system according to the present invention. This is a diagram illustrating the clock modulation of the optical communication system according to the present invention. This is a diagram illustrating the optical communication system according to the present invention. This is a diagram illustrating the optical communication system according to the present invention. This is a diagram illustrating the optical communication system according to the present invention. This is a diagram illustrating the optical communication system according to the present invention. This is a diagram illustrating the optical communication system according to the present invention.

[0020] Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, components having the same reference numerals are assumed to be the same components.

[0021] (Clock modulation) FIG. 4 is a diagram for explaining a transmission device 100 of an optical communication system according to the present embodiment. This optical communication system has an optical main signal S modulated with transmission data on a signal multiplexing axis 1. ｓｉｇ For this, clock modulation is performed to further modulate with a clock signal S on a signal multiplexing axis 2 orthogonal to the signal multiplexing axis 1. ｃｌｋ A multiplexed signal light L is transmitted through an optical transmission line 50 by a transmission device 100 that performs clock modulation. ｍｕｘ The transmission device 100 is provided.

[0022] When there are a plurality of optical main signals (S ｓｉｇ１ to S ｓｉｇＮ ), the transmission device 100 is characterized in that clock modulation is performed on each optical main signal on a signal multiplexing axis 3 orthogonal to both the signal multiplexing axis 1 and the signal multiplexing axis 2.

[0023] For the propagated light transmitted through an optical fiber, signal multiplexing axes such as light intensity, polarization, wavelength, phase, and spatial mode can be used. These signal multiplexing axes are orthogonal to each other, and another signal can be modulated for one propagated light. FIG. 3 is a conceptual diagram for modulating the propagated light with a main signal S ｓｉｇ and a clock signal S ｃｌｋ of an image sensor 11. The main signal S ｓｉｇ is modulated on multiplexing axis 1, and the clock signal S ｃｌｋ is modulated on multiplexing axis 2.

[0024] Furthermore, the modulation method using a plurality of multiplexing axes can also be applied to the case of parallel transmission in which there are a plurality of main signals. When the number of lanes of the main signal is N, each lane is assigned to channels 1 to N of the multiplexing axis 3, and a clock signal is modulated on each main signal (S ｓｉｇ１ to S ｓｉｇＮ ) on the multiplexing axis 2. For example, intensity modulation can be performed on the main signal, polarization modulation can be performed on the clock signal, and wavelength assignment can be used for parallelization of the main signal.

[0025] (Basic configuration of the optical communication system) Figure 5 is a diagram illustrating the optical communication system 300 of this embodiment. The optical communication system 300 receives the main signal S from the image sensor 11. ｓｉｇ and clock signal S ｃｌｋ This is a basic configuration for optical transmission. Here, we show the configuration when the number of lanes for the main signal is N. The optical communication system 300 includes a transmitting device 100 and a receiving device 200.

[0026] The transmitting device 100 includes an image sensor 11, an optical transmitter 54a, a clock modulator 54b, and a multiplexer 51. The number of lanes of the main signal output by the image sensor 11 is multiple (S ｓｉｇ１ ~S ｓｉｇＮ If this is the case, an optical transmitter is also placed for each lane (54a-1 to 54a-N).

[0027] The optical transmitters (54a-1 to 54a-N) receive each main signal (S ｓｉｇ１ ~S ｓｉｇＮ The device outputs signal light modulated on any multi-axis. This signal light is then incident on the clock modulator 54b. The clock modulator 54b clock modulates the signal light based on the clock signal on a multi-axis different from the multi-axis modulated by the optical transmitters (54a-1 to 54a-N). The multiplexer 51 incidents each of the clock-modulated signal lights into the optical transmission line 50 as a channel.

[0028] The receiving device 200 includes a demultiplexer 52, an optical receiver 53, a data extraction unit 17, and an image processor 12. Based on the modulation scheme of the clock modulation, the receiving device 200 samples the multiplexed signal light propagated in the optical transmission line 50 to acquire transmission data (main signal). The number of lanes of the main signal output by the image sensor 11 is multiple (S ｓｉｇ１ ~S ｓｉｇＮ In this case, an optical receiver is also placed for each lane (53-1 to 53-N). That is, the receiving device 200 separates each optical main signal which is multiplexed on the signal multiplexing axis 3 from the multiplexed signal light propagated in the optical transmission path 50, and samples each multiplexed signal light based on the modulation scheme of the clock modulation to acquire transmission data (main signal).

[0029] The signal light transmitted through each channel of the optical transmission path 50 is separated by the demultiplexer 52 and received by the optical receivers (53-1 to 53-N). The data extraction unit 17 samples the received data output by the optical receivers (53-1 to 53-N) according to a predetermined clock modulation scheme (modulation scheme of the clock modulator 54b) and extracts the main signal (S) output by the image sensor 11. ｓｉｇ１ ~S ｓｉｇＮ ) are obtained. These main signals (S ｓｉｇ１ ~S ｓｉｇＮ ) is input to the image processor 12.

[0030] (Embodiment 1) This embodiment describes an optical communication system 301 that performs intensity or phase modulation according to a main signal and switches the polarization state with a clock signal. Figure 6 is a diagram illustrating the optical communication system 301 of this embodiment.

[0031] The optical transmitter 54a has, for example, intensity or phase set as the signal multiplexing axis 1. The optical transmitter 54a receives the main signal S ｓｉｇ The light is modulated in intensity or phase to obtain the main optical signal L. ｓｉｇ Outputs the optical main signal L. ｓｉｇ The signal S is input to the clock modulation unit 54b. The clock modulation unit 54b is configured with, for example, two orthogonal polarizations as the signal multiplexing axis 2. ｃｌｋ In sync with the light main signal L ｓｉｇ The polarization state is periodically changed. The polarization state can be controlled using the Faraday effect, etc. The optical signal output by the clock modulator 54b is the clock signal S ｃｌｋ Information and light main signal S ｓｉｇ Since it also serves as information for the multiple signal light L, in this specification it is referred to as "multiplexed light L ｍｕｘ They call it that.

[0032] Multiplexed signal light L ｍｕｘ The light is injected into the optical transmission path 50. Here, if the optical transmission path 50 is an optical fiber, it is preferable to use an optical fiber with a fixed polarization state, such as a polarization-maintaining fiber, because this reduces the effect of lateral pressure on the optical fiber.

[0033] Multiplexed signal light L propagated through the optical transmission path 50 ｍｕｘThe light is incident on the demultiplexer 52 and separated into two polarization states used for polarization modulation. The polarization-separated optical main signal is received by receivers (53-1 and 53-2), and the received signal is input to the data extraction unit 17. The data extraction unit 17 samples the received signal based on pre-given clock modulation conditions and extracts the transmission data (main signal S ｓｉｇ ) obtain.

[0034] In Figure 6, the main signal S ｓｉｇ The case where the number of lanes is 1 was explained. Main signal S ｓｉｇ If there are multiple lanes, the main signal of each lane is assigned to the wavelength of the signal multiplexing axis 3, etc., and transmitted to the optical transmission path 50. At the receiving end, the signal is separated according to the wavelength of the signal multiplexing axis 3, and each is converted into a clock signal S. ｃｌｋ As mentioned earlier, sampling should be done using this information.

[0035] (Embodiment 2) This embodiment describes an optical communication system 302 that performs intensity or polarization modulation according to a main signal and switches the phase state with a clock signal. Figure 7 is a diagram illustrating the optical communication system 302 of this embodiment.

[0036] The optical transmitter 54a has, for example, intensity and polarization set as the signal multiplexing axis 1. The optical transmitter 54a receives the main signal S ｓｉｇ The light is modulated by intensity or polarization to obtain the main optical signal L. ｓｉｇ Outputs the optical main signal L. ｓｉｇ This is input to the clock modulation unit 54b.

[0037] The clock modulation unit 54b has, for example, phase set as the signal multiplexing axis 2. For example, the state from phase -π / 2 to π / 2 is defined as phase region 1, and the state from π / 2 to 3π / 2 is defined as phase region 2. The clock modulation unit 54b modulates the clock signal S ｃｌｋ In sync with the light main signal L ｓｉｇ The phase state is periodically changed between phase regions 1 and 2. A conventional modulator that generates a phase-modulated signal can be used in the clock modulation unit 54b.

[0038] The optical signal output by the clock modulator 54b is the clock signal S ｃｌｋ Information and light main signal S ｓｉｇSince it also serves as information for the multiple signal light L, in this specification it is referred to as "multiplexed light L ｍｕｘ It is called "multi-signal light L". ｍｕｘ It is injected into the optical transmission line 50.

[0039] Multiplexed signal light L propagated through the optical transmission path 50 ｍｕｘ The signal is received by receiver 53 and input to data extraction unit 17. Receiver 53 is equipped with a function to detect the phase state. For example, receiver 53 is an optical coherent receiver equipped with local light emission. The data extraction unit 17 samples the received signal based on pre-given clock modulation conditions and transmits the main signal S ｓｉｇ ) obtain.

[0040] In Figure 7, the main signal S ｓｉｇ The case where the number of lanes is 1 was explained. Main signal S ｓｉｇ If there are multiple lanes, the main signal of each lane is assigned to the wavelength of the signal multiplexing axis 3, etc., and transmitted to the optical transmission path 50. At the receiving end, the signal is separated according to the wavelength of the signal multiplexing axis 3, and each is converted into a clock signal S. ｃｌｋ As mentioned earlier, sampling should be done using this information.

[0041] In this embodiment, the main signal is intensity-modulated and the clock signal is phase-modulated, but it is also acceptable to phase-modulate the main signal and intensity-modulate the clock signal.

[0042] (Embodiment 3) In this embodiment, an optical communication system 303 that performs intensity or phase modulation according to a main signal and switches the propagation wavelength with a clock signal will be described. Figure 8 is a diagram illustrating the optical communication system 303 of this embodiment.

[0043] The optical transmitters (54a-1, 54a-2) have, for example, intensity or phase set as the signal multiplexing axis 1. The clock modulator 54b has wavelength set as the signal multiplexing axis 2, and specifically, it is a transmission wavelength selection unit that selects the transmission wavelength.

[0044] First, the main signal S ｓｉｇ This is input to the clock modulation unit 54b, which is a transmission wavelength selection unit. The clock modulation unit 54b selects two or more wavelength channels that can be transmitted in the optical transmission path 50 and the clock signal S ｃｌｋThe main signal S is synchronized with this. ｓｉｇ The signals are distributed to wavelength channels. Figure 8 shows an example with two wavelength channels (transmission wavelengths λ1 and λ2), but the number of wavelength channels may be three or more.

[0045] The main signal (S) is distributed to each wavelength channel. ｓｉｇ１ S ｓｉｇ２ The signals are input to optical transmitters (54a-1, 54a-2) that generate signal light of wavelengths λ1 and λ2, respectively. The optical transmitters (54a-1, 54a-2) then receive the main signal (S ｓｉｇ１ S ｓｉｇ２ Based on this, for example, light is modulated by intensity or phase, and the main light signal (L ｓｉｇ１ , L ｓｉｇ２ Outputs as (L). ｓｉｇ１ , L ｓｉｇ２ The signals are combined in the multiplexer 58 and output to the optical transmission line 50. The optical signal output by the multiplexer 58 is the clock signal S ｃｌｋ Information and light main signal S ｓｉｇ Since it also serves as information for the multiple signal light L, in this specification it is referred to as "multiplexed light L ｍｕｘ They call it that.

[0046] Multiplexed signal light L propagated through the optical transmission path 50 ｍｕｘ The light is incident on the demultiplexer 59, and the optical main signal (L) of each wavelength channel is received. ｓｉｇ１ , L ｓｉｇ２ ) is output. Light main signal (L ｓｉｇ１ , L ｓｉｇ２ The received main signal (S) is received by optical receivers (53-1, 53-2). ｓｉｇ１ S ｓｉｇ２ The data is input to the data extraction unit 17. The data extraction unit inputs the main signal (S) based on transmission wavelength selection conditions synchronized with a pre-given clock signal. ｓｉｇ１ S ｓｉｇ２ ) samples and transmits data (main signal S ｓｉｇ ) obtain.

[0047] In Figure 8, the main signal S ｓｉｇ The case where the number of lanes is 1 was explained. Main signal S ｓｉｇWhen the number of lanes is plural, the main signals of the respective lanes are assigned to polarization or the like of the signal multiplexing axis 3, transmitted through the optical transmission path 50, demultiplexed for each polarization of the signal multiplexing axis 3 on the receiving side, and each is sampled with the information of the clock signal S ｃｌｋ As described above, it may be sampled with the information of.

[0048] (Embodiment 4) In this embodiment, an optical communication system 304 that performs intensity or phase modulation according to a main signal and switches the spatial channel (core of an optical fiber or propagation mode) state with a clock signal will be described. FIG. 9 is a diagram for explaining the optical communication system 304 of this embodiment.

[0049] In this embodiment, a space division multiplexed optical fiber having a plurality of optical fibers arranged in parallel, a plurality of cores, or a plurality of propagation modes is used as the optical transmission path 50. The optical transmitter 54a has, for example, intensity or phase set as the signal multiplexing axis 1. The optical transmitter 54a outputs an optical main signal L obtained by modulating light with intensity or phase by the main signal S ｓｉｇ The optical main signal L ｓｉｇ is input to the clock modulation unit 54b. The clock modulation unit 54b has a spatial channel, for example, an optical fiber, a plurality of cores, or a plurality of propagation modes, set as the signal multiplexing axis 2. The clock modulation unit 54b selects two or more spatial channels and switches the transmission channel of the optical main signal L in synchronization with the clock signal S ｓｉｇ to the optical main signal (L ｃｌｋ ). FIG. 9 shows an example in which the number of spatial channels is 2, but the number of wavelength channels may be 3 or more. The multiplexer 61 outputs the optical main signal (L ｓｉｇ ), L ｓｉｇ１ ), to each spatial channel of the optical transmission path 50. ｓｉｇ２ ). ｓｉｇ１ ), L ｓｉｇ２ ).

[0050] The optical main signal (L ｓｉｇ１ ), L ｓｉｇ２ ) propagated through each spatial channel of the optical transmission path 50 is separated by the demultiplexer 62. The separated optical main signal is received by each optical receiver (53-1, 53-2), and the received signal is input to the data extraction unit 17. The data extraction unit 17 has a clock signal S given in advance ｃｌｋBased on the spatial channel selection conditions synchronized with the received signal (S ｓｉｇ１ S ｓｉｇ２ ) samples and transmits data (main signal S ｓｉｇ ) obtain.

[0051] In Figure 9, the main signal S ｓｉｇ The case where the number of lanes is 1 was explained. Main signal S ｓｉｇ If there are multiple lanes, the main signal of each lane is assigned to the wavelength of the signal multiplexing axis 3, etc., and transmitted to the optical transmission path 50. At the receiving end, the signal is separated according to the wavelength of the signal multiplexing axis 3, and each is converted into a clock signal S. ｃｌｋ As mentioned above, sampling can be done using this information. In this embodiment, instead of signal multiplexing axis 3, a number of spatial channels corresponding to the number of lanes may be provided (if 2 spatial channels are used for 1 lane, then for N lanes, there will be 2N spatial channels).

[0052] (Embodiment 5) Based on the configurations of Embodiments 1 to 4 described above, it is possible to connect multiple image sensors and multiple image processors in a mesh configuration. Figure 10 illustrates an optical communication system 305 as an example, which connects two transmitting devices (100-1, 100-2) each having an image sensor and three receiving devices (200-1 to 200-3) each having an image processor. The number of image sensors, the number of image processors, and the symmetry or asymmetry of their connections are not restricted.

[0053] The transmitting devices (100-1, 100-2) receive the clock signal S from the image sensor using the method described in Embodiments 1 to 4. ｃｌｋ and main signal S ｓｉｇ Multiplexing is performed. The multiplexer 151 outputs multiplexed signal light (L) from each transmitting device (100-1, 100-2). ｍｕｘ１ , L ｍｕｘ２ The light is multiplexed into channels such as wavelength and input to the optical transmission line 50. The demultiplexer 152 converts the multiplexed channel light propagated in the optical transmission line 50 into multiplexed signal light (L ｍｕｘ１ , L ｍｕｘ２ ) is split into two signals.

[0054] The path control unit 29 emits multiplexed signal light (L ｍｕｘ１ , Lｍｕｘ２ The path control unit 29 selects a route to distribute the multiplexed signal light (L) generated by the multiplexer 151 to receiving devices (200-1 to 200-3) having an image processor. ｍｕｘ１ , L ｍｕｘ２ If the multiplexing of ) is wavelength, the wavelength-selective switch and the multiplexer 151 perform the multiplexing of the signal light (L ｍｕｘ１ , L ｍｕｘ２ ) If the multiplexing is done through spatial channels such as cores or modes, it is an optical switch.

[0055] The receiving device (200-1 to 200-3) generates multiplexed signal light (L) using the method shown in Embodiments 1 to 4. ｍｕｘ１ , L ｍｕｘ２ ) to transmitted data (main signal S ｓｉｇ ) obtain.

[0056] The optical communication system 305 can transmit signals from any image sensor to image processors with different performance characteristics. Therefore, it is preferable that multiple image sensors can share various image processors, thereby economically enhancing the functionality of the camera system.

[0057] [Note] This invention relates to a parallel optical communication system technology that handles a clock signal and a main signal in parallel and transmits them via an optical transmission path that involves E / O conversion and O / E conversion in the intermediate transmission section. Parallel optical communication system technology generally has the problem that the group delay time differs between wavelength channels and spatial channels, causing a delay in the reception times of the optical clock signal and the optical main signal. This invention solves this problem with the following configuration.

[0058] [Configuration 1] An optical communication system having two or more uncoupled information multiplexing methods available for use in an optical transmission path, modulating a clock signal with one of the information multiplexing methods, modulating a main transmission signal with the other multiplexing methods, and demodulating the main transmission signal based on the clock signal.

[0059] [Configuration 2] The optical communication system according to Configuration 1, characterized in that it has an optical main signal transmitter that modulates a main transmission signal, a clock modulator that multiplexes a clock signal on the light emitted from the optical main signal transmitter, and a signal extraction unit that extracts a main transmission signal from the received light based on the multiplexed clock signal.

[0060] [Configuration 3] An image acquisition system characterized in that communication between an image sensor and an image signal processor is performed by the optical communication system described in Configuration 1 or 2.

[0061] 11: Image sensor 12: Image processor 13: Signal processing board 14: Clock branching unit 15: Transmission channel selection unit 17: Data extraction unit 20: Camera 24: Optical clock signal demultiplexer unit 27: Delay adjustment unit 29: Path control unit 30: Information processing unit 50: Optical transmission line 51: Multiplexer 52: Demultiplexer unit 53, 53-1, ..., 53-N: Optical receiver 54a, 54a-1, 54a-2: Optical transmitter 54b: Clock modulator 58, 61: Multiplexer unit 59, 62: Demultiplexer unit 100: Transmitter 151: Multiplexer 152: Demultiplexer 200: Receiving device 300-305: Optical communication system

Claims

1. An optical communication system comprising a transmitting device that transmits a clock-modulated multiplexed signal optical light via an optical transmission path, which is obtained by further modulating an optical main signal, modulated with transmission data on an arbitrary signal multiplexing axis, with a clock signal on another signal multiplexing axis orthogonal to the aforementioned arbitrary signal multiplexing axis.

2. The optical communication system according to claim 1, further comprising a receiving device that samples the multiplexed signal light propagated in the optical transmission path based on the modulation scheme of the clock modulation and acquires the transmission data.

3. The optical communication system according to claim 1, characterized in that, when there are multiple optical main signals, the transmitting device performs clock modulation on each of the optical main signals on an additional signal multiplexing axis that is orthogonal to both the arbitrary signal multiplexing axis and the other signal multiplexing axes.

4. The optical communication system according to claim 3, further comprising a receiving device that separates each of the optical main signals multiplexed on the other signal multiplexing axes from the multiplexed signal light propagated in the optical transmission path, and samples each of the multiplexed signal light based on the modulation scheme of the clock modulation to acquire the transmission data.

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