Signal processing device

Abstract

This signal processing device (10) comprises: a main signal line (L10) that extends from a connector (21) optically connected to a light source (30) to connectors (22A-22D) through a module (50) and transmits CW light; and a sub-signal line (L20) that branches from the main signal line (L10). The signal processing device (10) further comprises a processing unit (60) that is connected to the sub-signal line (L20) and that performs diagnostic processing for diagnosing the state of an optical transmission path for an optical signal including at least a portion of the main signal line (L10) via the sub-signal line (L20).

Description

Signal processing device

[0001] The present invention relates to a signal processing device such as a network switch.

[0002] Signal processing devices (for example, network switches) compatible with optical signals are known. A CPO (Co-packaged Optical) module (Non-Patent Document 1) may be used in such a signal processing device.

[0003] https: / / www.oiforum.com / wp-content / uploads / OIF-Co-Packaging-3.2T-Module-01.0.pdf , Implementation Agreement for a 3.2Tb / s Co-Packaged (CPO) Module (published March 29, 2023)

[0004] As a signal processing device using a CPO module, for example, the following configuration is conceivable. The signal processing device comprises a first connector optically connected to a light source, and a second connector optically connected to a device external to the signal processing device. The CPO module is optically connected to the first connector and the second connector. In a signal processing device using such a CPO module, an abnormality may occur in an optical transmission path for an optical signal from the light source.

[0005] An object of the present invention is to enable diagnosis of the state of an optical transmission path through which an optical signal from a light source is transmitted.

[0006] The signal processing device according to the present invention is a signal processing device comprising: a first connector configured to be optically connected to a light source that emits an optical signal; a second connector configured to be optically connected to an external device of the signal processing device; a CPO (Co-packaged Optical) module optically connected to the first connector and the second connector; a main signal line extending from the first connector through the CPO module to the second connector to transmit the optical signal, the main signal line including a first signal line connected to the first connector and a second signal line connected to the second connector; a sub-signal line branching from the main signal line; and a processing unit connected to the sub-signal line, the processing unit performing diagnostic processing to diagnose the state of the optical transmission path of the optical signal, including at least a portion of the main signal line, via the sub-signal line.

[0007] This configuration allows for the diagnosis of the state of the optical transmission path through which optical signals from a light source are transmitted.

[0008] Figure 1 is a diagram showing the main configuration of a signal processing device according to an embodiment of the present invention. Figure 2 is a flowchart of the diagnostic process. Figure 3 is a diagram showing the main configuration of a modified signal processing device. Figure 4 is a flowchart of the diagnostic process according to the modified version. Figure 5 is a diagram showing the main configuration of a modified signal processing device. Figure 6 is a flowchart of a part of the diagnostic process according to the modified version.

[0009] The signal processing device 10 according to this embodiment, shown in Figure 1, is configured as a network switch that transfers data to an optical network installed in a data center and performing distributed processing (for example, synchronous parallel computing by GPUs (Graphics Processing Units) in AI learning or big data processing). Specifically, the signal processing device 10 is configured to transfer packets from computing devices that constitute the optical network to other computing devices (including network switches) that constitute this optical network. Optical signals are used for packet transfer.

[0010] As shown in Figure 1, the signal processing device 10 includes a connector 21, connectors 22A to 22D (collectively referred to as "22"), a light source 30, a module 50, a processing unit 60, an interface 70, and a processor 90. The signal processing device 10 also includes optical waveguides L1, L3, L4A to L4D (collectively referred to as "L4"), and L5. As an example, connectors 21, connectors 22A to 22D, module 50, and processing unit 60 are mounted on a substrate (not shown) together with a packet transmission circuit (not shown) described later. Optical waveguides L3 to L5 may be waveguides directly provided on the substrate (for example, slab waveguides), or they may be optical fiber cables with connectors at both ends that are connected to the target of connection. Optical waveguide L1 consists of an optical fiber cable located outside the housing 11 of the signal processing device 10.

[0011] Each element shown in Figure 1 is used when processing and transmitting packets. Packet processing is performed by the processor 90. The actual signal processing device 10 also includes a packet transmission circuit that transmits packets input from any of the external devices EDa to EDd, which are computing devices constituting the optical network and are optically connected to connectors 22A to 22D, to the processor 90, but this circuit is not shown in the diagram. The packet transmission circuit includes a photoelectric conversion element (e.g., a photodiode) that converts packets input as optical signals to any of the connectors 22A to 22D into current signals, and a transimpedance amplifier (TIA) that converts the converted current signals into voltage signals. The packet transmission circuit further includes an A / D (analog / digital) conversion circuit that converts the voltage signals converted by the TIA into analog-to-digital signals. The packet transmission circuit inputs the packets converted into digital signals by the A / D conversion circuit to any of the ports 91A to 91D provided by the processor 90. Ports 91A to 91D and connectors 22A to 22D correspond to each other by the same alphabetical code. Packets input to connector 22A are photoelectrically converted by the packet transmission circuit and input to port 91A, which corresponds to connector 22A. The operation of processor 90 when a packet is input will be described later. Connectors to which packets are input may be provided separately from connectors 22A to 22D. The port of processor 90 to which packets are input may be provided separately from ports 91A to 91D.

[0012] Connectors 21, 22A to 22D, light source 30, and interface 70 penetrate the housing 11 of the signal processing device 10, with a portion of them exposed to the outside of the signal processing device 10. The other elements 30 to 60, 90, and L3 to L5 are housed inside the housing 11 of the signal processing device 10.

[0013] Connector 21 and light source 30 are optically connected by an optical waveguide L1 consisting of an optical fiber cable located outside the housing 11. The two cable connectors at both ends of the optical waveguide L1 are connected to the portion of connector 21 exposed from the housing 11 and the portion of light source 30 exposed from the housing 11, respectively. Connector 21 is optically connected to module 50 by an optical waveguide L3. Module 50 is optically connected to processing unit 60 by an optical waveguide L5. Light source 30 and module 50 are electrically connected to processing unit 60 and controlled by processing unit 60. Interface 70 is connected to processing unit 60.

[0014] Module 50 is optically connected to connector 22A by optical waveguide L4A. Similarly, module 50 is optically connected to connectors 22B to 22D by optical waveguides L4B to L4D. Connectors 22A to 22D are optically connected to external devices EDa to EDd, respectively, via optical waveguides such as optical fiber cables. Module 50 comprises a substrate 51, a splitter 52, optical modulators 53A to 53D (collectively referred to as "53"), a signal processing circuit 54, optical waveguides 55, 56A to 56D (collectively referred to as "56"), and 57A to 57D (collectively referred to as "57"). Module 50 is a CPO (Co-packaged optics) module, which is packaged using CPO. Specifically, the splitter 52, optical modulators 53A to 53D, and signal processing circuit 54 are mounted on the substrate 51, and the optical waveguides 55 to 57 are directly formed on the substrate 51, for example, as slab waveguides. In this configuration, each element of the module 50 is packaged. The module 50 may also include a housing to accommodate each element. As one form of CPO, there is NPO (Near-Packaged Optics), and the module 50 may take the form of an NPO module as an example of a CPO module. The module 50 also includes a module controller 59, etc.

[0015] The splitter 52 is optically connected to the optical waveguide L3 via the optical waveguide 55. The splitter 52 is optically connected to the downstream (later) optical modulators 53B to 53D via the optical waveguides 56A to 56D. The splitter 52 is further optically connected to the optical waveguide L5 via the optical waveguide 58. The optical modulators 53B to 53D are optically connected to the optical waveguides L4A to L4D via the optical waveguides 57A to 57D. The signal processing circuit 54 is electrically connected to the optical modulators 53B to 53D and controls them. The signal processing circuit 54 is electrically connected to the module controller 59 and controlled by the module controller 59. The signal processing circuit 54 is also electrically connected to the processor 90.

[0016] The processing unit 60 includes a detector 61 optically connected to the optical waveguide L5, a processor 62 electrically connected to the detector 61, and a memory 63 accessible by the processor 62.

[0017] Optical waveguides L3 to L4, splitter 52, optical modulator 53, and optical waveguides 55 to 57 constitute the main signal line L10. The main signal line L10 extends from connector 21 to connectors 22A to 22D and transmits CW light from light source 30. The main signal line L10 passes through module 50, which has a splitter 52, optical modulator 53, and optical waveguides 55 to 57. Optical waveguides L5 and 58 constitute the sub-signal line L20, which branches off from the main signal line L10.

[0018] Next, we will explain the details of each of the above elements.

[0019] The light source 30 includes a laser diode and emits CW (Continuous Wave) light, which is an optical signal modulated by the module 50 (optical modulators 53A to 53D), under the control of the processing unit 62.

[0020] CW light from the light source 30 is input to the connector 21 via the optical waveguide L1. The connector 21 is shaped to be optically connected to the light source 30. The CW light input to the connector 21 is input to the module 50 via the optical waveguide L3. The CW light input to the module 50 is input to the splitter 52 via the optical waveguide 55. The splitter 52 distributes the input CW light to the optical modulators 53A to 53D via the optical waveguides 56A to 56D, and also distributes it to the processing unit 60 via the optical waveguides 58 and L5.

[0021] Optical modulators 53A to 53D are individually controlled by the signal processing circuit 54 to modulate CW light. The CW light modulated by optical modulator 53A is input to connector 22A via optical waveguides 57A and L4A, and sent from connector 22A to external device EDa connected to connector 22A. Similarly, the CW light modulated by optical modulators 53B to 53D is input to connectors 22B to 22D via optical waveguides 57B to 57D and L4A to L4D, respectively, and sent to external devices EDb to EDd, respectively.

[0022] The signal processing circuit 54 consists of, for example, one or more IC (Integrated Circuit) chips. Examples of IC chips constituting the signal processing circuit 54 include a DSP (Digital Signal Processor) and a driver IC. The optical modulators 53A to 53D consist of, for example, Mach-Zehnder modulators. Ports 91A to 91D of the processor 90 are electrically connected to the signal processing circuit 54. As described above, the packet transmission circuit is also connected to ports 91A to 91D. For example, the DSP of the signal processing circuit 54 may constitute part of the packet transmission circuit. In this case, only the signal processing circuit 54 is connected to ports 91A to 91D.

[0023] The module controller 59 consists of, for example, one or more IC chips. Examples of IC chips include ASICs (Application Specific Integrated Circuits), FPGAs (Field-Programmable Gate Arrays), DSPs (Digital Signal Processing), CPUs (Central Processing Units), and microcomputers. The module controller 59 is controlled by the processor 62 and controls the operation of the module 50 (particularly the operation of the signal processing circuit 54 and the packet transmission circuit).

[0024] The processor 90 connected to the signal processing circuit 54 consists of a single ASIC chip, also known as a switch ASIC. The processor 90 may also consist of other IC chips on a single chip, such as an FPGA, DSP, CPU, or microcomputer. The processor 90 may also consist of a combination of multiple IC chips.

[0025] Here, the packet forwarding process by the processor 90 will be described. When a packet as an optical signal is input to connector 22A, one of the connectors 22A to 22D, the packet is converted into an electrical signal by the packet transmission circuit and input to the processor 90 from port 91A, which corresponds to connector 22A. The processor 90 refers to the MAC address table and outputs the packet from the port corresponding to the MAC address stored in the header of the input packet, one of the ports 91A to 91D, for example, port 91D. The packet output from port 91D is input to the signal processing circuit 54. The signal processing circuit 54 controls the optical modulator 53D connected to connector 22D, which corresponds to port 91D, the source of the input packet, based on the data (electrical signal) of the packet. The optical modulator 53D, which operates under this control, modulates the CW light input from the splitter 52. The modulated CW light is an optical signal representing the packet. This optical signal is output to the outside from connector 22D. As a result, the electrical signal indicating the packet from the processor 90 is converted into an optical signal and output. The signal processing circuit 54 controls the optical modulators 53A to 53C, other than the one being controlled in this case, so that CW light is not output to the connectors 22A to 22C. As a result, the optical signal is output only from connector 22D. Through the above processing, the signal processing device 10 performs packet forwarding. This packet forwarding process is performed each time a packet is input to any of the connectors 22A to 22D of the signal processing device 10.

[0026] As described above, the splitter 52 also distributes the CW light to the processing unit 60 via the optical waveguide L5. The processing unit 60 performs diagnostic processing to diagnose the state of the CW light optical transmission path (details will be described later) based on the signal state of the CW light. The CW light input to the processing unit 60 is input to the detector 61, which detects the signal state of the CW light.

[0027] The detector 61 includes a photoelectric conversion circuit that converts CW light into an electrical signal. The photoelectric conversion circuit includes, for example, a photoelectric conversion element such as a photodiode, a TIA, and an A / D conversion circuit. The photoelectric conversion element converts the input CW light into an analog current signal having a current value corresponding to the light intensity of the CW light. The TIA converts the converted analog current signal into an analog voltage signal. The A / D conversion circuit converts the analog voltage signal into a digital electrical signal and outputs the digital electrical signal to the processor 62. With this configuration, the detector 61 detects the light intensity, which is the signal state of the CW light, by converting the light intensity of the CW light into an electrical signal, and inputs the detected light intensity (electrical signal) to the processor 62.

[0028] The processor 62 includes a CPU and performs diagnostic processing by executing program 63P stored in memory 63. The processor 62 may consist of one or more IC chips that perform the diagnostic processing. Examples of IC chips include a CPU, ASIC, FPGA, DSP, and microcomputer.

[0029] The processor 62 performs, for example, the diagnostic process shown in Figure 2. The diagnostic process is performed, for example, when the signal processing device 10 is started up. The diagnostic process is for diagnosing the state of the CW optical transmission path.

[0030] In the diagnostic process, the processor 62 first controls the light source 30 to a low-power mode (step S11). As a result, CW light with a light intensity lower than that used for optical modulation is emitted from the light source 30. The emitted CW light is input to the processing unit 60 via the splitter 52 and the sub-signal line L20. The CW light input to the processing unit 60 is input to the detector 61. The detector 61 detects the light intensity of the CW light. The detected light intensity (electrical signal) is input to the processor 62.

[0031] The processor 62 acquires the light intensity of the CW light from the detector 61 (step S12), and diagnoses the state of the CW light transmission path from the light source 30 to the processing unit 60 based on the acquired light intensity (step S13). The processor 62 diagnoses that there may be an abnormality in the optical transmission path when the light intensity is lower than a preset first threshold. The processor 62 diagnoses that the optical transmission path is normal when the light intensity is equal to or greater than the first threshold.

[0032] When the light intensity is lower than the first threshold, it means that CW light with the desired light intensity is not reaching the detector 61, and there is a possibility that an abnormality has occurred in the CW light optical transmission path. For this reason, the processor 62 diagnoses that there is a possibility of an abnormality in the optical transmission path when the light intensity is lower than the first threshold. The CW light optical transmission path includes optical waveguide L1, connector 21, optical waveguide L3, optical waveguide 55, splitter 52, and sub-signal line L20 (optical waveguides 58 and L5). Among the CW light optical transmission path, optical waveguide L1 is a place where abnormalities are likely to occur. Optical waveguide L1 is made of an optical fiber cable and is connected to the connection target by a connector during assembly before the signal processing device 10 is started up, so an abnormality in the CW light optical transmission path may be a poor connection of the connector of optical waveguide L1 (for example, the connector coming loose). In addition, an open circuit or connector damage in optical waveguide L1 is also possible as an abnormality in the CW light optical transmission path. This also applies to optical waveguides L3 and L5 when they are made of optical fiber cables. However, since optical waveguide L1 is located outside the housing 11, it is more susceptible to external forces and is more prone to malfunctions than optical waveguides L3 and L5.

[0033] If the processor 62 diagnoses in step S13 that there is a possibility of an abnormality in the optical transmission path (step S13; No), it controls the light source 30 to terminate the operation of the light source 30, i.e., the emission of CW light (step S14). Furthermore, the processor 62 performs a process to notify the user of abnormality information indicating that there is a possibility of an abnormality in the optical transmission path of CW light (step S15). Note that there is also a possibility that there is an abnormality in the light source 30. For this reason, the abnormality information may include information indicating that there is also a possibility that there is an abnormality in the light source 30. Note that a failure of the light source 30 can be detected separately by monitoring a life signal periodically output from the light source 30, so the above statement does not need to be included in the abnormality information. The user includes the user and administrator of the signal processing device 10, as well as the installer of the signal processing device 10. This notification process includes the process of outputting the abnormality information to the interface 70. The interface 70 includes at least one of a user interface such as a display unit and an operation unit, and a communication interface connected to a predetermined external device. The processor 62 displays abnormal information on the user interface or to an external device via the communication interface. By checking this display, the user can recognize the abnormality and take action. The abnormal information may be a message prompting inspection of the optical fiber cable that is prone to malfunctions (for example, "Please inspect the optical fiber cable"). In particular, the abnormal information may be a message prompting inspection of the optical fiber cable connected to the optical waveguide L1, i.e., the light source 30, where malfunctions are most likely to occur (for example, "Please inspect the externally connected optical fiber cable"). When the user confirms via the interface 70 that an abnormality may have occurred, they take action to address the abnormality. After that, the user instructs the system to run the diagnostic process again by operating the user interface or other means.

[0034] If the processor 62 diagnoses that the optical transmission path for CW light is normal and the light intensity is above a first threshold (step S13; Yes), it controls the light source 30 to high power mode and initiates the packet forwarding process (step S16). The initiation process includes the processor 62 instructing the module controller 59 to start the packet forwarding process. Upon receiving this instruction, the module controller 59 activates the signal processing circuit 54, the packet transmission circuit, etc. The initiation process may also include activating the processor 90. In step S17, CW light with a light intensity stronger than that of CW light in low power mode is emitted from the light source 30, and the packet forwarding process, which is the original operation of the signal processing device 10, begins.

[0035] In this embodiment, CW light in high power mode is also continuously input to the processing unit 60 via the splitter 52. Therefore, the processor 62 periodically diagnoses the state of the CW light optical transmission path even after step S17 (step S17). This diagnostic process is the same as in steps S12 and S13. However, the threshold used for comparison with the light intensity is a second threshold instead of the first threshold. Since the CW light in step S17 is an optical signal in high power mode, the light intensity is inevitably higher than in step S13. Accordingly, the second threshold is set higher than the first threshold. If it is diagnosed in step S17 that there is a possibility of an abnormality in the optical transmission path, the processes in steps S14 and S15 are executed.

[0036] As described above, the signal processing device 10 comprises a connector 21, connectors 22A to 22D, a module 50, a main signal line L10, a sub-signal line L20, and a processing unit 60.

[0037] Connector 21 has a shape that allows it to be optically connected to a light source 30 that emits CW light, which is an optical signal. Connectors 22A to 22D have a shape that allows them to be optically connected to external devices EDa to EDd that constitute the optical network outside the signal processing device 10. Module 50 is a CPO module and is optically connected to connectors 21 and 22A to 22D. Note that the optical connection of the two elements as described above includes not only direct connection of the two elements via an optical waveguide without other optical elements such as optical switches, but also connection via other optical elements.

[0038] The main signal line L10 extends from connector 21 through module 50 to connectors 22A to 22D, transmitting CW light. The sub-signal line L20 branches off from the main signal line L10. The processing unit 60 is connected to the sub-signal line L20 and performs diagnostic processing to diagnose the state of the CW light optical transmission path (here, optical waveguide L1, connector 21, optical waveguide L3, optical waveguide 55, splitter 52, sub-signal line L20 (optical waveguides 58 and L5)) which includes a part of the main signal line L10, via the sub-signal line L20 (here, based on the CW light from the sub-signal line L20). Note that the CW light optical transmission path may include at least a part of the main signal line L10.

[0039] This configuration allows for the diagnosis of the state of the optical transmission path through which optical signals from a light source are transmitted.

[0040] Furthermore, module 50 includes a splitter 52 that constitutes the main signal line L10, and the sub-signal line L20 branches off from the main signal line L10 by being connected to the splitter 20. Since such a configuration can be realized with a simple hardware configuration, it has the advantage of having little negative impact on cost or implementation in relation to the usefulness of the function. This is especially true when the processing unit 60 is located outside module 50.

[0041] Furthermore, the processing unit 60 performs, as the aforementioned diagnostic processing, a first process of detecting the signal state (light intensity) of CW light from the secondary signal line L20, and a second process of diagnosing the state of the optical transmission path for CW light based on the detected signal state. With this configuration, the state of the optical transmission path for CW light can be diagnosed based on the optical signal from the light source 30 (in particular, the optical signal processed by the module 50).

[0042] Furthermore, the processing unit 60 includes a detector 61 that performs the first process and a processor 62 that performs the second process, whereby the first process and the second process are implemented with a simple configuration. Note that the detector 61 may be formed of, for example, a photoelectric conversion circuit that converts an optical signal into an electrical signal.

[0043] Note that the signal state may be, for example, reception quality, or may be information indicating whether or not the light intensity exceeds a threshold value. Such signal states may be detected by the detector 61 by providing a comparison circuit or the like in the detector 61.

[0044] The detector 61 may be provided inside the package of the module 50 by being mounted on the substrate 51 of the module 50 (see the alternate long and short dash line in FIG. 1). This allows the detector 61 to be incorporated into the module 50 for integrated manufacturing, which enhances the cost reduction effect.

[0045] Furthermore, as described above, the processing unit 60 performs a first control process to control the light source 30 and emit CW light of a first light intensity (low power mode) from the light source 30 as the first CW light. In addition, the processing unit 60 performs a diagnostic process in which it detects the signal state of the first CW light input from the sub-signal line L20 and diagnoses the state of the optical transmission line based on the detected signal state. Furthermore, when the processing unit 60 diagnoses that the state of the optical transmission line is normal based on the diagnostic process, it performs a second control process to control the light source 30 and emit CW light of a second light intensity (high power mode) stronger than the first light intensity from the light source 30 as the second CW light. With this configuration, the light intensity of the CW light can be lowered at a stage where it is unclear whether the state of the optical transmission line is normal or not. The CW light from the light source 30 generally has a high light intensity. This is because the CW light may be distributed by a splitter for use in multiple modulators and / or multiple modules, for example. If there is an abnormality in the CW light transmission path, the CW light may unintentionally strike other elements and destroy them, or the CW light may leak outside the signal processing device 10 and harm people in the vicinity. In this embodiment, when it is determined that the state of the optical transmission path is normal, the light intensity of the CW light is set to a low intensity, thereby suppressing damage to other elements and harm to people. This ensures the safety of the signal processing device 10. Harm to people is particularly relevant when the optical waveguide L1 (optical fiber cable) connecting the light source 30 and the connector 21 is located outside the housing 11. This is because if there is an abnormality in the optical waveguide L1, such as a disconnected connector, the CW light may strike people. The optical waveguide L1 may not be an element of the signal processing device 10, but may be attached externally to the signal processing device 10. In this case, the outside of the housing 11 can be said to be the outside of the signal processing device 10. This is the same throughout this specification.

[0046] Furthermore, in parallel with the modulation operation performed by the module 50 on the second CW light (modulation by the modulator 53), the processing unit 60 detects the signal state (light intensity) of the second CW light from the sub-signal line L20, and further performs a second diagnostic process of diagnosing the state of the optical transmission path based on the detected signal state. This enables diagnosis of the state of the optical transmission path even while the module 50 is in operation. When the processing unit 60 diagnoses that there is a possibility that an abnormality has occurred, it can stop the operation of the light source 30 or notify the user of the above-mentioned abnormality information.

[0047] Furthermore, as described above, when the processing unit 60 diagnoses through the above diagnostic processing that there is a possibility that an abnormality has occurred in the optical transmission path for CW light, it performs processing to stop the operation of the light source 30. This prevents the light source 30 from emitting CW light when there is an abnormality in the optical transmission path. It also reduces the risk of damage to other elements and harm to persons caused by the above-mentioned high-intensity CW light.

[0048] Furthermore, as described above, when the processing unit 60 diagnoses through the above diagnostic processing that there is a possibility that an abnormality has occurred in the optical transmission path for CW light, it performs processing to notify the user of abnormality information indicating that such a possibility exists. This notification allows the user to be informed of the possibility of an abnormality occurrence and prompted to perform an inspection.

[0049] Furthermore, as described above, the light source 30 included in the signal processing device 10 emits CW light to the outside of the housing 11, and the connector 21 and the light source 30 are optically connected by an optical fiber cable, which is the optical waveguide L1 outside the housing 11 (or outside the signal processing device 10). The abnormality information includes information (e.g., a message) prompting inspection of the optical fiber cable. This can prompt the user to inspect the optical fiber cable (optical waveguide L1), where abnormalities such as connector disconnection are likely to occur, making it easy for the user to detect abnormalities.

[0050] Furthermore, as described above, the signal processing device 10 further includes a processor 90 that performs packet forwarding processing. Module 50 receives an electrical signal indicating a packet to be forwarded by the processor 90, modulates an optical signal based on the input electrical signal to convert the electrical signal into an optical signal indicating a packet, and outputs the converted optical signal indicating the packet to the connector 22. This allows the signal processing device 10 to be used as a network switch.

[0051] (Modifications) Various modifications are possible to the configuration of the above embodiment. Examples of modifications are given below. Among the elements shown in each figure referenced in the modifications, elements that are the same as or corresponding to the elements in Figure 1 are given the same reference numerals as in Figure 1, and redundant explanations are omitted.

[0052] (Modification 1) The signal processing device 110 according to this modification, shown in Figure 3, has a processing device 160 instead of a processing device 60. The processing device 160 includes a back reflection meter 161 instead of a detector 61. The signal processing device 110 further includes a wavelength filter 140 between the connector 21 and the module 50. The wavelength filter 140 is optically connected to the connector 21 via an optical waveguide L2. The optical waveguide L2 is made of an optical fiber cable or a slab waveguide, similar to the optical waveguide L3. The wavelength filter 140 is optically connected to the module 50 via the optical waveguide L3. Furthermore, the wavelength filter 140 is connected to a back reflection meter (hereinafter also simply called a meter) 161 via an optical waveguide L5.

[0053] The main signal line L10 consists of optical waveguides L2 to L4, a wavelength filter 140, and elements 52, 53, 55 to 57 of module 50. The main signal line L10 also includes an upstream first signal line L11, a downstream second signal line L12, and a wavelength filter 140 positioned between them. The first signal line L11 consists of optical waveguide L2. The second signal line L12 consists of optical waveguides L3 to L4 and elements 52, 53, 55 to 57 of module 50. The sub-signal line L20 consists of optical waveguide L5.

[0054] The meter 161 inputs diagnostic light having a wavelength λ2 different from the CW light wavelength λ1 to the main signal line L10 via the optical waveguide L5, which is the sub-signal line L20. The diagnostic light passes through the wavelength filter 140, through the optical waveguide L2, connector 21, and optical waveguide L1, and is reflected by the light source 30. The reflected light, which is the diagnostic light reflected by the light source 30, passes through the optical waveguide L1, connector 21, and optical waveguide L2 and is incident on the wavelength filter 140. The wavelength filter 140 emits the incident reflected light on the sub-signal line L20 (optical waveguide L5), but does not emit it on the second signal line L12 (optical waveguide L3), which is in parallel with the sub-signal line L20. As a result, the diagnostic light is emitted from the meter 161, and its reflected light returns to the meter 161 and does not incident on the module 50. Furthermore, when CW light from the light source 30 is incident on the wavelength filter 140, it emits the CW light to the second signal line L12 but not to the sub-signal line L20. This prevents the CW light from being incident on the meter 161. The wavelength filter 140 includes, for example, a splitter optically connected to the first signal line L11 (optical waveguide L2), and first and second wavelength filters optically connected in parallel to the splitter. The first wavelength filter transmits only the light of wavelength λ1 (i.e., CW light) and the light of wavelength λ2 (i.e., diagnostic light or reflected light), while the second wavelength filter transmits only the latter. The first wavelength filter is optically connected to the second signal line L12 (optical waveguide L3). The second wavelength filter is optically connected to the sub-signal line L20 (optical waveguide L5). The splitter distributes the light from the first signal line L11 to a first wavelength filter and a second wavelength filter. The first wavelength filter transmits the light distributed by the splitter to the second signal line L12 when the light is of wavelength λ1 (i.e., CW light). The second wavelength filter transmits the light distributed by the splitter to the sub-signal line L20 when the light is of wavelength λ2 (i.e., reflected light). The second wavelength filter transmits the diagnostic light from the sub-signal line L20, i.e., light of wavelength λ2, and supplies it to the first signal line L11 via the splitter.

[0055] The meter 161 inputs diagnostic light to the main signal line L10 via the sub-signal line L20 (optical waveguide L5) to diagnose the state of the CW optical transmission path. The optical transmission path includes optical waveguides L1, L2, and L5, a connector 21, and a wavelength filter 140. The meter 161 can diagnose the state based on the light intensity of the reflected light from the diagnostic light, and / or the time from the emission of the diagnostic light to the reception of the reflected light. In particular, it diagnoses whether there is a possibility of an abnormality in the optical transmission path (or, in this case, whether an abnormality has occurred), and the location of the abnormality. The diagnostic results are output to the processor 62. Based on the diagnostic results, the processor 62 performs processing such as stopping the operation of the light source and notifying abnormality information.

[0056] The processor 62 executes the diagnostic process shown in Figure 4 instead of the diagnostic process shown in Figure 2. The diagnostic process is executed, for example, when the signal processing device 110 is started up. First, the processor 62 starts the meter 161 (step S21) and diagnoses the state of the CW optical transmission path using the meter 161 (step S22). The processor 62 determines whether the diagnostic result indicates that there is a possibility of an abnormality occurring in the CW optical transmission path (step S23). If the diagnostic result indicates the above (step S23; Yes), the processor 62 stops the meter 161 (step S24) and notifies the abnormality information (step S25). The abnormality information may indicate that there is a possibility of an abnormality occurring in the CW optical transmission path (including that an abnormality has occurred), as well as the location of the abnormality. Further explanation of step S25 is the same as the explanation of step S15. When the user confirms that there is a possibility of an abnormality occurring via the interface 70, they take action against this abnormality. After that, the user instructs the diagnostic process to be executed again by operating the user interface or the like.

[0057] If the diagnostic result indicates that the CW optical transmission path is normal (step S23; No), the processor 62 activates the light source 30 and performs the packet forwarding process to start (step S26). The start process is the same as the start process in step S16 of the above embodiment, so the explanation is omitted.

[0058] The processor 62 then periodically diagnoses the state of the CW optical transmission path using the meter 161 and determines whether the diagnosis result indicates that there is a possibility of an abnormality in the CW optical transmission path (steps S27 and S28). The diagnosis and determination are the same as in steps S22 and S23. If the diagnosis result indicates that there is a possibility of an abnormality in the CW optical transmission path (step S28; Yes), the processor 62 stops the operation of the light source 30, module 50, etc., and then returns to step S24.

[0059] As described above, the processing unit 60 is equipped with a meter 161 that inputs diagnostic light to the main signal line L10 via the sub-signal line L20 to diagnose the state of the CW optical transmission path. This allows for diagnosis of the possibility of an abnormality occurring in the optical transmission path and the location of the abnormality. This enables smooth identification of the cause of the abnormality, thereby reducing the loss of time required for recovery in the event of an abnormality. Furthermore, the processing unit 60 is equipped with a processor 62 that performs the above diagnostic processing by diagnosing the state of the CW optical transmission path using the meter 161 and performs processing according to the diagnostic results (such as notification of abnormality information), thus enabling processing according to the diagnostic results. Because the meter 161 is installed on the wavelength filter 140 on the main signal line L10, the distribution of CW light to the meter 161 is suppressed, and the principle loss of CW light to the module 50 is suppressed.

[0060] (Modification 2) The signal processing device 210 according to this modification, shown in Figure 5, has wavelength filters 240A to 240D (collectively referred to as "240") instead of wavelength filter 140, compared to the signal processing device 110. Each wavelength filter 240 has the same configuration as wavelength filter 140, so a detailed explanation is omitted. Connector 21 is optically connected to module 50 via optical waveguide L3. Module 50 has optical output ports Pa to Pd (collectively referred to as "P") that are optically connected to optical waveguides 57A to 57D, respectively. Optical waveguides L4A to L4D, which are optically connected to optical output ports Pa to Pd, respectively, are optically connected to wavelength filters 240A to 240D, respectively. Connectors 22A to 22D are optically connected to wavelength filters 240A to 240D via optical waveguides L6A to L6D (collectively referred to as "L6"). The wavelength filter 240 is connected in parallel to the downstream optical waveguides L5 and L6. The wavelength filter 240 transmits diagnostic light to the upstream side of the main signal line L10, transmits CW light only to optical waveguide L6, and transmits reflected diagnostic light only to optical waveguide L5. Wavelength filters 240A to 240D are connected to the optical switch 280 via optical waveguides L5A to L5D (collectively referred to as "L5"). Optical waveguides L5 and L6D may be waveguides provided on a substrate (for example, slab waveguides) or optical fiber cables.

[0061] Examples of optical switches 280 include waveguide switches using thermo-optical effects with MEMS (Micro Electro Mechanical Systems), PLC (Planar Lightwave Circuit), or silicon photonics, and waveguide switches using electro-optical effects with compound semiconductors. The optical switch 280 is controlled by the processor 62. The meter 161 is optically connected to the optical switch 280 via an optical waveguide L7 (such as an optical fiber cable or slab waveguide). The optical switch 280 switches the connection destination of the optical waveguide L7 to one of the optical waveguides L6A to L6D under the control of the processor 62. This allows the supply destination of the diagnostic light from the meter 161 to one of the wavelength filters 240A to 240D, and further to one of the input ports Pa to Pd.

[0062] The main signal line L10 of the signal processing device 210 consists of optical waveguides L3, L4, and L6, elements 52, 53, 55-57, and P of module 50, and a wavelength filter 240. The first signal line L11 consists of optical waveguides L3 to L4, and elements 52, 53, 55-57, and P. The second signal line L12 consists of optical waveguide L6. The sub-signal line L20 consists of optical waveguides L5 and L7 and an optical switch 280.

[0063] The processor 62 performs the processing shown in Figure 6, for example, between step S21 and step S24 or S26. That is, the processor 62 operates the meter 161 to diagnose the state of the CW optical transmission path (step S22). For example, if the optical switch 280 connects optical waveguide L7 and optical waveguide L5A, the diagnostic light propagates through optical waveguides L5A and L4A, through port Pa, through optical waveguide 57A, optical modulator 53A, and optical waveguide 56A, and the reflected light returns via the reverse route. This diagnoses the state of the optical transmission path, which includes optical waveguide 57A, optical modulator 53A, and optical waveguide 56A, one of the main signal lines L10 branching within module 50. After that, step S23 is performed. Here, if the state is normal (step S23), the processor 62 determines whether step S22 etc. was performed with all optical waveguides L5 as the connection destination of optical waveguide L7 (step S23A). If the determination result is negative, it controls the optical switch 280 to switch the connection destination of optical waveguide L7 (i.e., the connection destination of meter 161) (step S23B). After that, step S22 is performed again. If the determination result is positive, step S24 is executed. It is preferable that the same processing as in Figure 6 be performed during periodic state checks between steps S26 and S29.

[0064] As described above, the status of each signal line branching within module 50 (each combination of optical waveguide 57, optical modulator 53, and optical waveguide 56) is individually diagnosed. The abnormal information reported in step S25 may include information that identifies which signal line may have an abnormality, for example, by the port number. This allows the user to easily understand which line within module 50 may have an abnormality. The meter 161 may be optically connected to optical waveguides L5A to L5D (i.e., wavelength filters 240A to 240B) and configured to output diagnostic light to each of the optical waveguides L5A to L5D individually. In this case, the optical switch 280 is not required. Such a meter 161 may include, for example, four back reflection meters connected to each of the optical waveguides L5A to L5D.

[0065] As described above, the main signal line L10 is branched into at least a first line (optical waveguide 57A, etc.) and a second line (optical waveguide 57B, etc.) within the module 50. The module 50 includes an optical output port Pa that is optically connected to the first line and outputs CW light from the first line to connector 22A, and an optical output port Pb that is optically connected to the second line and outputs CW light from the second line to connector 22B. The optical transmission path for CW light includes the first line and the second line, and the sub-signal line L20 includes the first and second sub-signal lines (optical waveguides L5A, L5B). The meter 161 diagnoses the state of the first line by inputting diagnostic light to the optical output port Pa via the first sub-signal line, and diagnoses the state of the second line by inputting diagnostic light to the optical output port Pb via the second sub-signal line. This configuration allows for individual diagnosis of the status of the two parallel signal lines branched within module 50. Furthermore, since the optical switch 280 switches the optical connection destination with meter 161 between the first sub-signal line and the second sub-signal line, individual diagnosis of the status of the two parallel signal lines is facilitated.

[0066] (Modification 3) The optical waveguide L1 may be located inside the housing 11 instead of outside it. In this case, the light source 30 and the connector 21 may be located inside the housing 11 of the signal processing device 10. The hardware configuration of each element described above is arbitrary. The light source 30 only needs to emit an optical signal, and may emit an optical signal other than CW light. At least one of each element, such as the processor 62, optical switch 280, and meter 161, may be mounted on the substrate 51 of the module 50 and located inside the package of the module 50. The signal processing device 10 may be configured as a device other than a network switch. The signal processing device 10 may be configured as a device that processes the optical signal from the light source by modulation or the like. The processor 90 may be configured as a device that performs processing other than packet forwarding. For example, the processor 90 may perform predetermined processing and output the processing result data to the CPO module, and the CPO module may convert the processing result data, i.e., the electrical signal, into an optical signal by modulating the optical signal from the light source based on the processing result data. Program 63P should be stored in a computer-readable, non-temporary storage medium such as a storage device. The number of each of the above elements, such as the number of connectors 22, can be changed arbitrarily.

[0067] (Scope of the Invention) The present invention is not limited to the embodiments and modifications described above. For example, the present invention includes various modifications to the embodiments and modifications described above that can be understood by those skilled in the art within the scope of the technical concept of the present invention. The configurations listed in the embodiments and modifications described above can be combined as appropriate to the extent that they do not contradict each other. It is also possible to delete any of the above configurations.

[0068] (Note) The following are examples of configurations that use the above embodiments and modified examples as one example. Only any part of the above embodiments and modified examples may be applied to each note. Also, parts of each note may be combined. (Note 1) A signal processing device comprising: a first connector configured to be optically connected to a light source that emits an optical signal; a second connector configured to be optically connected to an external device of the signal processing device; a CPO (Co-packaged Optical) module optically connected to the first connector and the second connector; a main signal line that extends from the first connector through the CPO module to the second connector and transmits the optical signal, the main signal line including a first signal line connected to the first connector and a second signal line connected to the second connector; a sub-signal line branching from the main signal line; and a processing unit connected to the sub-signal line, which performs diagnostic processing to diagnose the state of the optical transmission path of the optical signal including at least a part of the main signal line via the sub-signal line. (Note 2) The signal processing apparatus according to Note 1, wherein the CPO module comprises a splitter that constitutes the main signal line, and the sub-signal line branches off from the main signal line by being connected to the splitter. (Note 3) The signal processing apparatus according to Note 1 or 2, wherein the processing unit performs, as the diagnostic processing, a first processing which detects the signal state of the optical signal from the sub-signal line, and a second processing which diagnoses the state of the optical transmission line based on the detected signal state. (Note 4) The signal processing apparatus according to Note 3, wherein the processing unit comprises a detector that performs the first processing and a processor that performs the second processing. (Note 5) The signal processing apparatus according to Note 4, wherein the detector is provided within the package of the CPO module.(Note 6) The signal processing device according to any one of Notes 3 to 5, wherein the processing unit performs: a first control process to control the light source and emit an optical signal of a first optical intensity from the light source as a first optical signal; a diagnostic process to detect the signal state of the first optical signal input from the sub-signal line and diagnose the state of the optical transmission path based on the detected signal state; and a second control process to control the light source and emit an optical signal of a second optical intensity stronger than the first optical intensity as a second optical signal from the light source when the diagnostic process diagnoses that the state of the optical transmission path is normal. (Note 7) The signal processing device according to Note 6, wherein the processing unit further performs a diagnostic process to detect the signal state of the second optical signal from the sub-signal line and diagnose the state of the optical transmission path based on the detected signal state, in parallel with the modulation operation of the second optical signal by the CPO module. (Note 8) The signal processing device according to Note 6 or 7, wherein the first connector is formed in a shape that is optically connected to the light source by an optical fiber cable located outside the signal processing device. (Note 9) The signal processing apparatus according to Note 1, wherein the processing unit includes a back reflection meter that inputs diagnostic light to the main signal line via the sub-signal line to diagnose the state of the optical transmission path. (Note 10) The signal processing apparatus according to Note 9, wherein the main signal line includes an upstream first signal line, a downstream second signal line, and a wavelength filter disposed between the first signal line and the second signal line, wherein the sub-signal line is optically connected to the wavelength filter in parallel with the second signal line, the wavelength of the optical signal and the wavelength of the diagnostic light are different, the wavelength filter emits the optical signal from the first signal line to the second signal line without emitting it to the sub-signal line, and emits the reflected light of the diagnostic light from the first signal line to the sub-signal line without emitting it to the second signal line.(Note 11) The signal processing apparatus according to either Note 9 or 10, wherein the main signal line is branched into at least a first line and a second line within the CPO module, the second connector includes a second-first connector and a second-second connector, the CPO module includes a first optical output port optically connected to the first line and outputting the optical signal from the first line to the second-first connector, and a second optical output port optically connected to the second line and outputting the optical signal from the second line to the second-second connector, the optical transmission path includes the first line and the second line, the sub-signal line includes first and second sub-signal lines, the back reflection meter diagnoses the state of the first line by inputting the diagnostic light to the first optical output port via the first sub-signal line, and diagnoses the state of the second line by inputting the diagnostic light to the second optical output port via the second sub-signal line. (Note 12) The signal processing device according to Note 11, further comprising an optical switch that switches the optical connection destination with the back reflection meter to the first sub-signal line and the second sub-signal line. (Note 13) The signal processing device according to any one of Notes 1 to 12, further comprising the processing unit which, when the diagnostic processing determines that there is a possibility of an abnormality occurring in the optical transmission path of the optical signal, further performs a process to stop the operation of the light source. (Note 14) The signal processing device according to any one of Notes 1 to 13, further comprising the processing unit which, when the diagnostic processing determines that there is a possibility of an abnormality occurring in the optical transmission path of the optical signal, further performs a process to notify the user of an abnormality indicating that such a possibility exists. (Note 15) The signal processing device according to Note 14, further comprising the light source, the light source which emits the optical signal to the outside of the signal processing device, the first connector and the light source which are optically connected by an optical fiber cable outside the signal processing device, and the abnormality information which includes information prompting inspection of the optical fiber cable.(Note 16) The signal processing device according to any one of Notes 1 to 15, further comprising a processor that performs packet forwarding processing, wherein the CPO module receives an electrical signal indicating the packet to be forwarded by the processor, modulates the optical signal based on the input electrical signal to convert the electrical signal into an optical signal indicating the packet, and outputs the converted optical signal indicating the packet to the second connector.

[0069] 10...Signal processing unit, 11...Housing, 21...Connector, 22...Connector, 22A-22D...Connector, 30...Light source, 40...Optical switch, 50...Module, 51...Circuit board, 52...Splitter, 53...Optical modulator, 53A-53D...Optical modulator, 54...Signal processing circuit, 55-57...Optical waveguide, 56A-56D...Optical waveguide, 57A-57D...Optical waveguide, 59...Module controller, 60...Processing unit, 61...Detector, 62...Processor, 63...Memory, 63P...Program, 70...Interface -Face, 90...Processor, 91A-91D...Port, 110...Signal processing unit, 140...Wavelength filter, 161...Back reflection meter, 210...Signal processing unit, 240A-240D...Wavelength filter, 280...Optical switch, EDa-EDd...External device, L1-L7...Optical waveguide, L4A-L4D...Optical waveguide, L5A-L5D...Optical waveguide, L6A-L6D...Optical waveguide, L10...Main signal line, L11...First signal line, L12...Second signal line, L20...Sub-signal line.

Claims

1. A signal processing device comprising: a first connector configured to be optically connected to a light source that emits an optical signal; a second connector configured to be optically connected to an external device of the signal processing device; a CPO (Co-packaged Optical) module optically connected to the first connector and the second connector; a main signal line extending from the first connector through the CPO module to the second connector to transmit the optical signal, the main signal line including a first signal line connected to the first connector and a second signal line connected to the second connector; a sub-signal line branching from the main signal line; and a processing unit connected to the sub-signal line, the processing unit performing diagnostic processing to diagnose the state of the optical transmission path of the optical signal, including at least a portion of the main signal line, via the sub-signal line.

2. The signal processing apparatus according to claim 1, wherein the CPO module includes a splitter that constitutes the main signal line, and the sub-signal line is branched from the main signal line by being connected to the splitter.

3. The signal processing apparatus according to claim 1, wherein the processing unit comprises a detector for detecting the signal state of the optical signal from the sub-signal line, and a processor for diagnosing the state of the optical transmission line based on the detected signal state, and the detector is provided within the package of the CPO module.

4. The signal processing apparatus according to claim 1, wherein the processing unit performs: a first control process to control the light source and emit an optical signal of a first optical intensity from the light source as a first optical signal; a diagnostic process to detect the signal state of the first optical signal input from the sub-signal line and diagnose the state of the optical transmission path based on the detected signal state; a second control process to control the light source and emit an optical signal of a second optical intensity stronger than the first optical intensity from the light source as a second optical signal when the diagnostic process diagnoses that the state of the optical transmission path is normal; and a diagnostic process to detect the signal state of the second optical signal from the sub-signal line and diagnose the state of the optical transmission path based on the detected signal state, in parallel with the modulation operation of the second optical signal by the CPO module.

5. The signal processing apparatus according to claim 1, wherein the processing unit includes a back reflection meter that inputs diagnostic light to the main signal line via the sub-signal line to diagnose the state of the optical transmission path.

6. The signal processing apparatus according to claim 5, wherein the main signal line comprises an upstream first signal line, a downstream second signal line, and a wavelength filter disposed between the first signal line and the second signal line, the sub-signal line is optically connected to the wavelength filter in parallel with the second signal line, the wavelength of the optical signal is different from the wavelength of the diagnostic light, the wavelength filter emits the optical signal from the first signal line to the second signal line without emitting it to the sub-signal line, and emits the reflected light of the diagnostic light from the first signal line to the sub-signal line without emitting it to the second signal line.

7. The signal processing apparatus according to claim 5, wherein the main signal line is branched into at least a first line and a second line within the CPO module, the second connector includes a second-first connector and a second-second connector, the CPO module includes a first optical output port optically connected to the first line and outputting the optical signal from the first line to the second-first connector, and a second optical output port optically connected to the second line and outputting the optical signal from the second line to the second-second connector, the optical transmission path includes the first line and the second line, the sub-signal line includes first and second sub-signal lines, the back reflection meter diagnoses the state of the first line by inputting the diagnostic light to the first optical output port via the first sub-signal line, and diagnoses the state of the second line by inputting the diagnostic light to the second optical output port via the second sub-signal line.

8. The signal processing apparatus according to claim 7, further comprising an optical switch that switches the optical connection destination with the back reflection meter to the first sub-signal line and the second sub-signal line.

9. The signal processing apparatus according to claim 1, wherein the processing unit further performs a process to stop the operation of the light source when the diagnostic process determines that there is a possibility of an abnormality occurring in the optical transmission path of the optical signal.

10. The signal processing apparatus according to claim 1, wherein the processing unit further performs a process to notify the user of an abnormality indicating that there is a possibility of an abnormality occurring in the optical transmission path of the optical signal when the diagnostic process determines that there is a possibility of such an abnormality.

11. The signal processing apparatus according to claim 10, further comprising the light source, wherein the light source emits the optical signal to the outside of the signal processing apparatus, the first connector and the light source are optically connected by an optical fiber cable outside the signal processing apparatus, and the abnormal information includes information prompting inspection of the optical fiber cable.

12. The signal processing apparatus according to claim 1, further comprising a processor that performs packet forwarding processing, wherein the CPO module receives an electrical signal indicating the packet to be forwarded by the processor, modulates the optical signal based on the input electrical signal to convert the electrical signal into an optical signal indicating the packet, and outputs the converted optical signal indicating the packet to the second connector.

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