Light source device

Abstract

We provide a light source device that improves the quality of maintenance and operation of equipment that includes an optical engine using CPO (Co-packaged Optics). [Solution] In a light source system, a light source device 100 includes multiple pluggable light source modules 50, 51, some of which can be set as spare light sources. The light source device 100 includes an optical switch 102 that selects light from the spare light source, an optical coupler 103 that combines the light from the currently used light source module 50 and the selected light, and a CPU 105 that controls the output of the combined light from the optical coupler 103 without reducing the optical output level from the light source device 100. The optical switch 102 can guide light from the spare light source module 51 to any input port of the optical coupler 103.

Description

[Technical Field]

[0001] The present invention relates to a light source device for a light engine. [Background technology]

[0002] The rapid spread of generative AI is accompanied by a significant increase in internet traffic. It is said that global internet traffic will be 3,000 times greater by 2050. In data centers that handle generative AI, in addition to general-purpose CPUs, a huge number of GPUs are connected via high-capacity, low-latency networks, operating as if they were a single giant GPU. Optical signal processing is being introduced to replace electrical signal processing, which has limitations in operating speed and power consumption, for computing to process the large amounts of data in data centers.

[0003] Datacenters use switching equipment and optical transceivers. The use of optical transceivers has changed from long-distance transmission of several hundred kilometers between datacenters to short-distance data transmission of several tens of meters between servers within a datacenter, and even several meters between GPUs and CPUs. Along with this change, the development of photonics-electronic convergence devices that replace electrical signal processing with optical signal processing is accelerating. In photonics-electronic convergence devices, the integration of electrical and optical devices is progressing while shortening the distance between electrical devices such as DSPs and IP switches and electrical-optical converters.

[0004] In datacenters that require high-volume traffic processing, clusters of numerous GPUs are connected via switch equipment. Optical transceivers further shorten the electrical signal wiring and adopt near-package mounting techniques such as NPO (Near Package Optics) and CPO (Co-packaged Optics), which place the ASICs close to the periphery of the switch equipment. CPO is a mounting technique in which an ASIC and an optical transceiver are densely mounted on a common substrate (co-package) with minimal surface area. The ASIC is, for example, a switch IC, and the optical transceiver includes a multi-channel modulator and photodetector (PD) based on silicon photonics. CPO-based optical transceivers are also called optical engines. By placing multiple optical engines close to the four sides of the ASIC and shortening the electrical transmission distance, it is possible to increase the speed and reduce the power consumption of switch equipment and GPUs.

[0005] Optical transceivers have been developed with a pluggable configuration that allows them to be inserted and removed from the front panel of the equipment. However, optical engines using CPOs are mounted on a circuit board inside the switch equipment, and are therefore not easily accessible from the front panel of the equipment. Because the optical engine is not a pluggable configuration, ease of operation, including maintenance and expansion, plays an important role in determining system performance for equipment that uses CPOs. For each channel of the optical engine, a carrier light for the transmitter and a local light for the receiver must be supplied from a light source. For equipment that includes a CPO-based optical engine, various considerations must be given to the light source as well. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] https: / / www.oiforum.com / wp-content / uploads / OIF-ELSFP-01.0.pdf [Non-patent document 2] https: / / epic-photonics.com / wp-content / uploads / 2021 / 12 / Robert-Blum-Intel.pdf Summary of the Invention [Problem to be solved by the invention]

[0007] In devices that include a CPO-based optical engine, the optical engine and the ASIC are located close to each other, so the large heat generated by the ASIC increases the temperature of the optical engine. This can adversely affect the performance and reliability of the light source for the optical engine. Therefore, attention has been focused on a light source for the optical engine that has a replaceable, pluggable form and is intended to be placed on the front panel of the device.

[0008] FIG. 10(a) is a diagram showing a light source configuration for a conventional optical engine. It schematically shows a configuration in which the light source is arranged outside the optical engine in a device 10 including an optical engine. The device 10 with an external light source 13 is composed of an ASIC 12 arranged on a substrate and multiple optical engines 11 arranged around it. Light is supplied to each optical engine from the multiple external light sources 13 arranged at the edge of the substrate via optical fibers 14. Each optical engine 11 transmits and receives optical signals on multiple channels to and from outside the device.

[0009] Standardization organizations such as the Optical Internetworking Forum (OIF) have defined electrical specifications such as the number of light sources and wavelengths, as well as mechanical specifications such as housing, for external light sources for devices using CPO-based optical engines. Known form factors include the External Laser Source (ELS) and External Laser Small Form-Factor Pluggable (ELSFP) (Non-Patent Document 1).

[0010] Figure 10(a) shows the case where the external light source 13 is a pluggable ELSFP form factor. A certain distance can be placed between the optical engine 11 and the external light source 13, which reduces the impact of heat generated by the ASIC 12 on the light source. Because the ELSFP is a pluggable external light source, it can be replaced on the front panel of the device, making it highly maintainable. Generally, light sources have a higher failure rate than optical engines, so the external light source 13 must be replaced after a certain period of time. The ELSFP is designed to be replaced upon failure, and interruptions to service for connected optical engines are unavoidable during the replacement process. Furthermore, since multiple external light sources 13 are installed on the board mounting the optical engine 11 and ASIC 12, it is difficult to design the overall cooling.

[0011] FIG. 10(b) is another diagram showing a light source configuration for a conventional optical engine. It schematically shows a configuration in which a light source is located inside the optical engine (see Non-Patent Document 2). The optical engine 20 in FIG. 2(b) has a silicon photonic integrated circuit (PIC) 21 mounted on a substrate. The silicon PIC 21 integrates a modulator 22, redundant laser light sources 23, and a holding mechanism (groove) 24 for a fiber array. Optical signals are input and output via fibers connected to the silicon PIC 21. The redundant laser light sources 23 have two systems of laser light sources for 16 channels, providing complete redundancy. Since the laser light sources 23 are included in the CPO-based optical engine, they are more susceptible to heat generated by the ASIC. However, due to the complete redundancy of the laser light sources 23, the optical engine 20 is more reliable than the configuration in FIG. 10(a), in which the light sources are located outside the optical engine.

[0012] However, in Non-Patent Document 2, it is unclear how to switch between the redundantly configured laser light sources, and while switching operation between the two light sources, the service of the optical engine of the failed channel is interrupted. Furthermore, if both laser light sources of the two systems fail, the optical engine of the corresponding channel becomes unusable. As described above, the light source configuration for optical engines in the prior art could not avoid service interruptions of the equipment including the optical engine when a light source fails. The quality of maintenance and operation of equipment using optical engines with CPO was also insufficient. The present invention has been made in consideration of the above-mentioned problems, and provides a light source device that improves the quality of maintenance and operation of a device that includes a CPO-based optical engine. [Means for solving the problem]

[0013] One aspect of the present invention is a light source device comprising: a plurality of light source modules each including a plurality of light source elements; an optical switch that selects and outputs light from a portion of the plurality of light source modules that can be set as a spare; an optical coupler that combines light from a first light source module of the plurality of light source modules with selected light from a second light source module of the portion of the light source modules; and a processor that controls the optical SW and the plurality of light source modules, wherein the optical switch is configured to combine light of any channel of the second light source module with light of a specific channel of the first light source module. [Effects of the Invention]

[0014] The light source device of the present invention improves the quality of maintenance and operation of equipment including a CPO-based optical engine. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram showing a configuration of a light source system including a light source device according to the present disclosure. [Figure 2] 1 is a diagram showing the configuration of a light source device according to a first embodiment that can switch light sources without interruption. [Figure 3] 10A and 10B are diagrams illustrating the operation of uninterrupted switching in the light source device of the present disclosure. [Figure 4] FIG. 10 is a diagram showing the configuration of a light source device in which the number of spare settings is reduced according to the second embodiment. [Figure 5] 10 is a diagram showing the configuration of a light source device in which the range of the light SW of the third embodiment is limited. FIG. [Figure 6] FIG. 10 is a diagram showing an example of an arrangement of light source devices according to the present disclosure in a data center. [Figure 7] FIG. 10 is a diagram showing the configuration of a light source device according to a fourth embodiment, which is provided with a light monitor circuit. [Figure 8] FIG. 10 is a diagram showing the configuration of a light source device according to a fifth embodiment, which is provided with an optical monitor circuit. [Figure 9] FIG. 1 illustrates a control protocol between a light source device of the present disclosure and a target device. [Figure 10] FIG. 1 illustrates a prior art light source configuration for a light engine. DETAILED DESCRIPTION OF THE INVENTION

[0016] The light source device disclosed herein includes a plurality of pluggable light source modules, some of which can be configured as spare light sources. The light source device includes an optical switch that selects light from the spare light source, and an optical coupler that combines the selected light with light from the working light source module. The light source device further includes a processor configured to control output of the combined light from the optical coupler without reducing the optical output level from the light source device. The optical switch is configured to direct light from the spare light source module to any input port of the optical coupler.

[0017] The light source device of the present disclosure can be applied to any device requiring multiple light sources. Target devices include, for example, optical switch devices that include a CPO-based optical engine and signal processing devices such as GPUs. The light source device of the present disclosure and the target device can be connected not only by optical fiber, but also by electrical wiring to exchange control signals. A control protocol between the light source device and the target device enables optimal light supply to maximize the performance of the optical engine.

[0018] The following will first provide an overview of a light source system including a light source device according to the present disclosure, then describe the detailed configuration and operation of the light source device, and further describe the control protocol used in the light source system.

[0019] FIG. 1 is a diagram showing the configuration of a light source system including a light source device according to the present disclosure. The light source system includes a light source device 100, a device 200 to which light is supplied from the light source device, and optical feed cables 300-1 to 300-n connecting the two devices. The light source device 100 includes multiple pluggable light source modules 101, each of which is configured to be attachable to and detachable from the light source device 100. The light source modules can output multiple lights of different wavelengths or the same wavelength, and can operate as, for example, an 8-channel or 16-channel light source. For example, they may be ELS light sources or ELSFP light sources defined by the OIF.

[0020] Light of multiple channels corresponding to one light source module is supplied from the light source device 100 to a corresponding light feed cable via one of transmission interfaces (TxIF) 104-1 to 104-n. The other end of the light feed cable 300-1 to 300-n opposite the TxIF is connected to reception interfaces (RxIF) 204-1 to 204-n of the target device 200.

[0021] The TxIFs 104-1 to 104-n represent optical output mechanisms from the light source device 100 and are physical optical connectors. The optical feed cables are detachable from the TxIFs, and each of the TxIFs 104-1 to 104-n may be a pair of mating male and female optical connectors. The RxIFs 204-n also represent optical input mechanisms to the target device 200 and may be physical optical connectors. The RxIFs 204-1 to 204-n may also be a pair of mating male and female optical connectors. The optical connectors described above are capable of inputting and outputting both optical and electrical signals. Note that if the control protocol described with reference to FIG. 9 is not used, electrical signals are not required, and therefore conventional MPO connectors can be used. Even when an MPO connector is used, a latch mechanism that works in conjunction with the MPO connector can be provided on the board of the light source device 100 to recognize the insertion of the MPO connector as the TxIFs 104-1 to 104-n.

[0022] In the light source system of FIG. 1, the optical feed cable is a bundle of eight fibers 301 corresponding to eight channels of light, but there is no limitation on the number of channels. The light output from one light source module via one TxIF can be, but is not limited to, eight or sixteen channels. Also, in FIG. 1, light is illustrated as being supplied from the light source device 100 via n optical feed cables, but several optical feed cables may be combined into one. Similarly, the TxIFs 104-1 to 104-n may not be separate optical connectors that mate with each other, but may be a connector that combines several TxIFs. The same applies to the RxIFs 204-1 to 204-n.

[0023] The target device 200 to which light is supplied from the light source device 100 can be any device that requires multiple lights, but the following description will be given of a signal processing device including CPO-based optical engines 201-1 to 202-2n as an example. The target device 200 includes an ASIC 203 and a processor 205 such as a CPU. In the target device 200 of FIG. 1, four lights are supplied to each of two optical engines, but there are no limitations on the number of optical engines, the number of lights supplied, or other configurations.

[0024] Each of the light feed cables 300-1 to 300-n also includes electrical wiring 302 for transmitting and receiving control signals 122 and 221, and a control protocol, which will be described later, is implemented between the light source device 100 and the target device 200. Below, the detailed configuration and operation of the light source device 100 of the present disclosure and various embodiments will be described, and the control protocol between the light source device and the target device will also be described.

[0025] FIG. 2 is a diagram showing the configuration of a light source device according to a first embodiment, capable of switching to a backup light source without momentary interruption. It corresponds to the light source device 100 shown in FIG. 1. The light source device 100 in FIG. 2 includes a plurality of pluggable light source modules 101, specifically 2n light source modules 50-1 to 50-n, 51-1 to 51-n. As described above, each light source module is configured to be detachable from the light source device 100, and is capable of outputting a plurality of light beams having different wavelengths or the same wavelength. In the configuration example shown in FIG. 2, each light source module can operate as a light source that outputs eight independent channels of light. The number of channels is not limited to eight, and may be, for example, 16.

[0026] The light source module contains light source elements such as laser elements and related optical circuits for the number of channels. It also contains electrical circuits for exchanging control signals that externally control the operation of the laser elements (LDs) and electrical signals such as status information for the laser elements. For example, it may be an ELS light source or an ELSFP light source as defined by the Optical Fiber Interface (OIF). The light source device 100 includes n TxIFs 104-1 to 104-n, each of which supplies eight channels of light to an external target device.

[0027] The light source device 100 includes 2n light sources and outputs light from n TxIFs. This means that it includes twice the number of light source modules compared to the conventional light source configuration shown in FIG. 10(a). In the light source device 100 of FIG. 2, half of the light source modules (n) are configured as active light source modules 50-1 to 50-n, and the remaining n are configured as spare light source modules 51-1 to 51-n adjacent to the active light source modules. The light source device 100 includes twice the number of light source modules required for output light. It should be noted that the light source device of the present disclosure can have all 2n light source modules with the same mechanical and electrical specifications. The configuration of the light source device 100 of FIG. 2 illustrates the use of the light source modules at a certain point in time. Therefore, over time, if a light source element (LD) fails and the light source module is replaced, the positions of the active and spare light source modules may change. The state of the light source modules in FIG. 2 should be understood as, for example, an initial setting state when the light source device 100 starts service.

[0028] The light source device 100 includes an optical switch 102 (optical SW) that can switch and select light from 2n light source modules to any output port. The optical SW 102 has a maximum of (2n x 8) input ports to which the light from the 2n light source modules is input, and a maximum of (2n x 8) output ports from which selected light is output. Details of the optical SW 102 will be described later.

[0029] Furthermore, the light source device 100 includes n optical couplers 103-1 to 103-n, each with two inputs and one output (2×1), that combine output light from the active light source module with output light from the spare light source module via an optical SW. Each of the n optical couplers corresponds one-to-one to the n TxIFs 104-1 to 104-n. Therefore, output light from the optical coupler passes through one TxIF and becomes output light from the light source device 100 as is. The light source device 100 outputs half (n×8) of the (2n×8) light beams that can be output from the 2n light source modules.

[0030] In Figure 2, the optical SW 102 is depicted as a single block, but this represents the path switching function and does not mean that it is a single component. Eight channels of light from one active light source module correspond to one optical coupler and one TxIF. For example, the eight channels of light from active light source module 50-1 are output directly via the corresponding optical coupler 103-1 and TxIF 104-1. Therefore, light from the active light source module simply needs to be output straight to the optical coupler, as shown by the white arrows from the input port to the output port in the optical SW 102. Note that for active light source modules, the path within the optical SW 102 can be fixed, path selection is not required, and the path does not necessarily need to go through the optical SW. In this case, the optical SW 102 only needs to have (n x 8) input ports and (n x 8) output ports.

[0031] Light from the spare light source module must be guided to any input port of the corresponding optical coupler. Therefore, the optical SW 102 can select any path between the input port connected from the spare light source module and the output port connected to the corresponding optical coupler. Specifically, an 8x8 optical SW is configured between the eight input ports to which eight channels of light from the spare light source module 51-1 are input and the eight output ports connected to the corresponding optical coupler 103-1.

[0032] The path switching setting of the optical SW 102 is performed by a control signal 123 from a processor 105 such as a CPU. The processor 105 also supplies a control signal 122 via the TxIF. Furthermore, information regarding the state of the light source can be exchanged with the light source module. For example, a CMIS (Common Management Interface Specification) signal 121 can be used.

[0033] If the optical SW 102 can switch any input port to any output port, the maximum flexibility can be achieved in setting it as a working light source module or a backup light source module. However, since the size of the optical SW 102 becomes large, the configuration of the optical SW 102 can be simplified by limiting the use of at least some of the light source modules to working or backup. For example, it should be noted that some light source modules located in positions limited to working use only can be configured to be directly connected to an optical coupler without going through the optical SW 102, as described above. Furthermore, the configuration of the optical SW 102 can be simplified by reducing the number of light source modules that can be set as backups, rather than providing twice the required number of light source modules as shown in Figure 2. Such setting of light source module use and variations in the optical SW configuration will be described later as another embodiment with reference to Figures 4 and 5.

[0034] The light source device of the present disclosure is equipped with an optical SW 102 and an optical coupler 103, which allows light from the active light source module and light from the backup light source module to be combined and output. By simultaneously controlling the output levels of the two lights from the active and backup light source modules, fluctuations in the level of the output light from the TxIF 104 of the light source device 100 are suppressed. Switching from light from the active light source module to light from the backup light source module can be performed without interruption.

[0035] FIG. 3 is a diagram illustrating the hitless switching operation in the light source device of the present disclosure. The operation of switching the output from one TxIF 104 from the output light of one working light source module 50 to the output light of one backup light source module 51 is described. (a) of FIG. 3 is a schematic diagram illustrating the connection state of two light source modules, one working and one backup, that can be connected to one TxIF 104. Only a portion of the optical SW 102 related to the two light source modules 50 and 51 is shown. (b) of FIG. 10 is a diagram illustrating the change over time in the output light level at three points A, B, and C in the configuration of (a).

[0036] For simplicity, the following explanation will be given assuming that all wavelengths of light from the light source modules are the same wavelength (λ0). For example, if we consider a switch device operating in the DR system as the target device, the light source modules supply light of the same wavelength to the optical engine. The eight channels of light from the active light source module and the backup light source module all have the same wavelength (λ0). Because the wavelengths are the same, light from a failed channel of the active light source module (described later) can be replaced by light from any of the channels of the backup light source module.

[0037] On the other hand, different wavelengths (λ1, λ2, λ) per core of the fiber n In an FR switching device that uses wavelength division multiplexing transmission, which operates with light of λ1, λ2, λ3, and λ4, light of different wavelengths is output from a single light source module. For example, in the case of an FR system that uses four different wavelengths (λ1, λ2, λ3, λ4), a light source module that outputs eight channels can output eight light of wavelengths (λ1, λ2, λ3, λ4, λ1, λ2, λ3, λ4). Because the wavelengths differ depending on the channel, there are limitations on the channels that can be used in a spare light source module. In the following explanation, it is assumed that all the light from the light source modules has the same wavelength (λ0).

[0038] 3(a), eight channels of light from the working light source module 50 are input to eight input ports of the optical SW 102 via optical fiber 111 (point A). The channel light from the working light source module 50 is input to one input port of the optical coupler 103 via the output port of the optical SW 102 and optical fiber 112. The output port (point C) of the optical coupler 103 is in a state where the eight channels of light from the working light source module 50 are output as is. It is assumed that all channels of the working light source module 50 are operating normally. The eight channels of light from the working light source module 50 are also output at the output of the TxIF 104. At this time, it is assumed that all channels of the spare light source module 51 are unused and the light source is stopped.

[0039] Let's consider a case where a change in the state of the light source element occurs in the light source of the first channel of the currently used light source module 50. The light source module 50 is equipped with a mechanism that can detect malfunctions or signs of malfunctions in the operation of the light source element that occur internally. This malfunction can be detected in advance using status information from the light source. For example, an increase in the current or a slight decrease in the output level of the light source element can be information that predicts a malfunction of the light source element. Specifically, the OIF ELSFP CMIS specification defines that information on bias current and output power can be acquired from the light source module 50. When a malfunction is detected, the light source element of any channel of the backup light source module 51 is activated and combined with the light of the channel where the malfunction occurred.

[0040] The example of FIG. 3(a) shows a case where a light source element of a third channel that is available at that time is selected in the spare light source module 51. The path of the optical SW 102 is selected to combine the light of the first channel that has failed in the working light source module 50 with the light of the third channel of the spare light source module 51 using the optical coupler 103. The output port of the optical SW 102 is connected to the optical coupler 103 in a fixed positional relationship via optical fibers 112 and 114. By setting the internal path of the optical SW 102 as shown in FIG. 3(a) using a control signal 123 from the processor 105, the light from the two light source modules 50 and 51 is output in a combined state at the output port side of the optical coupler 103. Furthermore, in the light source device of the present disclosure, the levels of the output light from the two light source modules 50 and 51 are synchronized and gradually increased and decreased, respectively, so that the output light can be supplied to the target device without interruption in the TxIF 104.

[0041] Figure 10(b) shows a schematic diagram of the change in light level over time at points A, B, and C. The vertical axis represents the light level, with Low representing the state where output is stopped and Hi representing the specified output light level. The light output levels from the two light source modules 50 and 51 are controlled by a control signal (CMIS) sent from the processor to the light source modules. The horizontal axis represents time, which will be explained as (i) "Period 1" up to t1, (ii) "Period 2" from t1 to t2, and (iii) "Period 3" from t2 onwards.

[0042] During "period 1" (to t1), light from the currently used light source module 50 (hereinafter referred to as the first light source module) is selected by the optical SW 102 and output directly from the TxIF 104. Here, it is assumed that, based on the status information from the first light source module, an abnormality in the current of the light source element (LD) and an abnormality in the output light level are detected in the first channel of the first light source module. Based on the received status information, the processor checks available channels in the spare light source module 51 (hereinafter referred to as the second light source module). When the processor confirms that the third channel of the spare light source module 51 is available, it sets a path connecting the third input port of the optical SW 103 to the first output port of the ports connected to the optical coupler 103 via the optical fiber 114.

[0043] When the path setting of the optical SW 103 is completed, the light of the first channel of the first light source module 50 and the light of the third channel of the second light source module 51 are ready to be combined. Here, the third channel of the second light source module 51 is still in a stopped state, and the optical output level at point B is Low.

[0044] During "Period 2" (t1 to t2), the output light level of the third channel of the second light source module 51 is gradually increased from a stopped state to a Hi level. In synchronization with this increase in the output light level, the output light level of the first channel of the first light source module 50 is gradually decreased from Hi to a stopped state. The rate of increase and decrease may be linear or non-linear. As long as the rate of increase and decrease corresponds, the light level at point C on the output side of the optical coupler 103 can be maintained at a constant level throughout the entire period.

[0045] During "Period 3" (t2~), the light source element of the first channel of the first light source module 50 is in a stopped state. After the light source element is in a stopped state, the power supply to this light source element can also be stopped. Meanwhile, the third channel of the second light source module 51 is at a specified output light level. The light of the first channel is output continuously via the optical coupler 103 and the TxIF 104 without level fluctuations or interruptions. The path from the first channel of the first light source module 50 in the optical SW 102 may be disconnected.

[0046] By controlling the output light levels of the two light source modules and switching the path of the optical SW 102 as described above, optical output can be transmitted without interruption between the working light source module 50 and the backup light source module 51. After switching the light source modules as shown in FIG. 3, only the first channel of the working light source module 50 is stopped, but over time, a failure may occur in the light source element of another channel. When such a failure is anticipated, a new path for the optical SW 102 can be set so that the light of that other channel can be combined with the light of the light source element of any channel available in the backup light source module 51.

[0047] As time passes and the uninterruptible switching procedure shown in FIG. 3 is repeated, the light source module 50 reaches a state where, for example, half of the channels are stopped. At this stage, the light source module 50 can be replaced. For example, by replacing all channels of the light source module 50 using all channels of the light source module 51 that were set as a spare, the light source of the light source module 50 can be completely stopped and the replacement work can be performed. At this time, the spare light source module 51 operates in the same state as the original working light source module 50. As such, it should be noted that the indications of working and spare in FIGS. 2 and 3 merely represent the "main use" of the light source module at a given point in time. Planned replacement work can be performed uninterruptedly through various operational maintenance procedures without affecting the target device. Therefore, the light source device 100 of the present disclosure shown in FIG. 2 is suitable for target devices that require high reliability and cannot tolerate interruptions in operation.

[0048] The operation described in FIG. 3 illustrates a case where hitless switching is performed between a working light source module 50 and a backup light source module 51. This is because half of the 2n light source modules (n) are set as backup light source modules in the light source device 100 shown in FIG. 2. If two adjacent light source modules in FIG. 2 are considered to be light source modules 50 and 51 in FIG. 3, hitless switching can be performed by combining two light source modules. When two light source modules are set as a pair in advance in this manner, the light source module set as the working module at the start of operation does not necessarily need to be connected via the optical switch 102. In other words, the light source module set as the working module may be connected directly to the corresponding optical coupler 103 without passing through the optical switch 102. Even in this case, hitless switching as shown in FIG. 3 can be performed as long as the switching between the working and backup modules is performed within the range of the combination of two adjacent light source modules.

[0049] For example, after replacing the light source module 50 described above, the light source module in the replaced position can now be considered a spare light source module, and the hitless switching shown in FIG. 3 can be performed. In this way, among the multiple light source modules in the light source device disclosed herein, it is sufficient that the optical SW 102 can perform path switching only for the light source module that can be set as a spare. By restricting the combination of active and spare light source modules as shown in FIG. 2, the number of optical SW paths can be reduced, thereby reducing the size of the optical SW. The number of spare light source modules can be determined based on the failure rate of the light source elements in the light source module, the number of channels per light source module, the total number of channels in the light source device, etc. The optical SW configuration can be determined based on the number of spare light source modules expected in advance.

[0050] Fig. 4 is a diagram showing the configuration of a light source device in which the number of spare light source modules set according to the second embodiment is reduced. Light source device 100-1 includes n light source modules 50-1 to 50-n and one light source module 51 that can be set as a spare. The configuration, which includes an optical SW 102, n optical couplers 101-1 to 103-n, and corresponding n TxIFs 104-1 to 104-n, is the same as that of light source device 100 shown in Fig. 2. In Fig. 4, n TxIFs are provided corresponding to the n light source modules 50-1 to 50-n, and if eight channels of light are output from the light source modules, the same number of lights as light source device 100 of the first embodiment shown in Fig. 2 can be supplied.

[0051] The difference between the light source device 100 of the first embodiment and the light source device 100-1 of FIG. 2 is that the number of light source modules that can be set as spares is limited to one among the (n+1) multiple light source modules. If the failure rate of the light source elements of the light source modules is very low, setting half of the light source modules as spares as in the configuration of the first embodiment is wasteful, resulting in a large total number of light source modules. If a very low failure rate is expected, the position of the light source module 51 set as spare can be determined as shown in FIG. 4, and the optical SW 102 can be configured to support hitless switching for all other active light source modules. For example, as shown in FIG. 4, it is sufficient to set a path (black arrow) connecting the input port of the optical SW to which the fiber of the spare light source module 51 is connected to one input port of one of the n optical couplers. This allows for a smaller number of input ports of the optical SW 102 than the light source device 100 of the first embodiment. Furthermore, the paths within the optical SW from the n currently used light source modules may be fixed as indicated by the white arrows, and therefore may be directly connected to the optical coupler 103 without passing through the optical SW 102 .

[0052] Even in a configuration with a limited number of spare light source modules as shown in Figure 4, if the frequency of failures is low, the probability of multiple light source modules failing simultaneously is low. Even if one light source module fails, there is often enough time for practical maintenance work before the next failure occurs, so there is a high possibility that the replacement work for the failed active light source module can be carried out without interruption. The number of spare light source modules can be adjusted taking into account the failure rate of the light source elements in the light source modules and the allowable time for service outage. The position of the light source module 51 that can be set as a spare is not limited to the configuration at the end as shown in Figure 4, but can be anywhere.

[0053] Fig. 5 is a diagram showing the configuration of a light source device in which the range of the optical SWs of the third embodiment is limited. Light source device 100-2 includes n light source modules 50-1 to 50-n and two light source modules 51-1 and 51-2 that can be set as spares. The configuration, which includes an optical SW 102, n optical couplers 101-1 to 103-n, and corresponding n TxIFs 104-1 to 104-n, is the same as that of light source device 100 shown in Fig. 2. In Fig. 5, n TxIFs are provided corresponding to the n light source modules 50-1 to 50-n, and if eight channels of light are output from the light source modules, the same number of lights as in light source device 100 of the first embodiment shown in Fig. 2 can be supplied to the target device.

[0054] The difference from the light source devices of the embodiments shown in Figures 2 and 4 is that the range of working light source modules covered by one light source module that can be set as a spare is limited in advance, thereby reducing the scale of the optical SW. One spare light source module 51-1 is limited to perform uninterrupted switching operations for n / 2 light source modules 50-1 to 50-2 / n+1, half of the n (for simplicity, an even number) working light source modules. One optical SW 102-1 only needs to be able to set routes to the input ports of n / 2 optical couplers, so the number of ports on the output side can be halved. The routes within the optical SW from the n / 2 working light source modules can be fixed, as shown by the white arrows, and therefore they may be directly connected to the n / 2 optical couplers without passing through the optical SW 102-1. As described above, the light source device of the present disclosure only requires that some of the multiple light source modules can be set as spares. By limiting the positions of the multiple light source modules that can be set as spares, the number of paths required for the optical SW to be selected can be reduced.

[0055] Fig. 6 is a diagram showing an example of the arrangement of light source devices in a data center. Fig. 6 shows an arrangement image of the front panel side of a GPU server rack 1000 and a network SW rack 1001 in the data center. The light source devices 100, 100-1, and 100-2 described so far correspond to light source devices 1010 arranged at high positions in each rack. The light source device 1010 shown in Fig. 6 only shows the current light source, the spare light source, and the TxIF 104 that are expected to be replaced.

[0056] The GPU server rack 1000 includes GPU servers 1012-1 and 1012-2 and is connected to a light source device 1010 via an optical feed cable 300-1. The GPU servers 1012-1 and 1012-2 correspond to the target devices 200 in the light source system of FIG. 1 and include optical engines using CPOs (not shown). The network SW rack 1001 includes network SWs 1013-1 and 1013-2 and is connected to the light source device 1010 via an optical feed cable 300-2. The network SWs 1013-1 and 1013-2 also correspond to the target devices 200 in the light source system of FIG. 1 and include optical engines using CPOs (not shown). Optical signals from the GPU servers and network SWs are connected to other racks via ports 1014 of a patch panel.

[0057] In a device including a CPO-based optical engine, considering the normal failure rate, the light source element, such as an LD, in the light source has the highest failure frequency. When the light source device 1010 is installed at a high position in a server rack, the light source module can be replaced very easily on the front panel. The light source module replacement work described with reference to FIG. 3 can be performed efficiently, improving the operability of data centers. Furthermore, since the light source device of the present disclosure is connected to the target device via a TxIF, optical feed cable, and RxIF, the replacement work can be standardized regardless of the type of target device housed in the rack. Furthermore, since the light source module of the light source device 1010 is an ELSFP-type light source incorporating a light source element, such as an LD, there is no optical fiber on the front surface of the ELSFP module.

[0058] As shown in FIG. 10(a) as a conventional technique, in the case of a device 10 using an ELSFP without redundancy, a form without a built-in light source is often used. In this case, light from a separate external light source needs to be supplied to the ELSFP via fiber. The front panel of the device required many fibers to supply light sources. With the light source device 1010 of the present disclosure, it is only necessary to insert a small ELSFP module into the front panel, eliminating the need to change fiber connections, which also improves the operability of data centers.

[0059] The TxIF and RxIF can be arranged on the front panel or rear of the light source device 1010. When the TxIF and RxIF are arranged on the front panel side, the fan is arranged on the rear side of the light source device. This arrangement is advantageous in terms of airflow design near the light source device 1010. When the TxIF and RxIF are arranged on the rear side, the optical feed cables 300-1 and 300-2, through which high-power light flows, are also arranged on the rear side, which is advantageous in terms of operational safety. Once the optical feed cables are wired when the light source device starts operating, there is little chance that they will need to be rewired thereafter. By arranging the TxIF and RxIF on the rear side, the safety of maintenance work on the front panel side can be ensured. When the light source device disclosed herein is deployed in a data center as described above, the ease of replacing the light source module and the simplicity of the fiber wiring on the front panel can significantly improve operational efficiency and safety.

[0060] The light source device of the present disclosure performs the hitless switching operation shown in Fig. 3 based on the light source element status information (CMIS) obtained from the light source module. The status information is sufficient to predict a failure of the light source element, but if the light source device further includes a mechanism for monitoring the quality of the output light from the light source module, more accurate failure detection can be performed and the hitless switching operation of the light source device can be ensured.

[0061] 7 is a diagram showing the configuration of a light source device according to a fourth embodiment of the present disclosure, which includes an optical monitor circuit. Similar to FIG. 4, the light source device 100-3 in FIG. 7 includes a plurality of light source modules 101, an optical switch 102, an optical coupler 103, and a TxIF 104, except that the position of the spare light source module is different. The light source device 100-3 further includes an optical monitor circuit 106 controlled by a processor 105 and connected to the output port of the optical switch 102. The optical monitor circuit includes photodiodes (PDs) for eight channels, converts light from the light source modules into electrical signals 124, and determines the optical output level based on the electrical signals 124.

[0062] The optical switch 102 is configured to enable routing that connects the output light from all light source modules to the optical monitor circuit 106. The output light of a specific channel from the light source module can be connected to the optical monitor circuit 106 to detect the optical output level. For a specific channel, the hitless switching shown in Figure 3 can be performed to temporarily connect it to the optical monitor circuit 106, making it possible to grasp the output light level of the specific channel in use.

[0063] If there is no problem with the optical output level of the monitored channel, the hitless switching shown in Figure 3 can be performed again to return to the original working light source module state. If the optical output level of the monitored channel deviates from the expected value, calibration can be performed on the light source element of that channel. If the optical output level of the monitored channel deviates significantly from the expected value, operation with the spare light source module can be continued.

[0064] FIG. 8 is a diagram showing the configuration of a light source device according to a fifth embodiment of the present disclosure, which includes an optical monitor circuit. The light source device 100-4 in FIG. 8 is configured to constantly monitor the optical output levels of all channels from the active light source module. A second optical coupler 107 with one input and two outputs is provided between the optical coupler 103 and the TxIF 104, corresponding to one TxIF. The second optical coupler 107 branches the input light at a ratio of 1:99, with 1% branched to the optical monitor circuit 106 and 99% branched to the TxIF 104. The optical monitor circuit 106 outputs an electrical signal 124, allowing the processor 105 to grasp the output optical level of each channel from the active light source module. This makes it possible to constantly monitor the optical output level.

[0065] 3 can be performed based on the electrical signal 124 from the optical monitor circuit 106 in addition to the status information from the light source module. By monitoring the output light level from the light source module in real time, the accuracy of fault detection in the light source element can be improved.

[0066] 9 is a diagram showing an example of a control protocol between a light source device and a target device according to the present disclosure. The diagram shows a sequence illustrating the exchange of information and operations that may be performed between the light source device and the target device (light engine). As described in FIG. 1, the optical feed cable connecting the two devices may also include electrical wiring 302 that can exchange electrical signals, and the control protocol of FIG. 9 is implemented between the light source device 100 and the target device 200.

[0067] The control protocol of FIG. 9 determines in S1 whether the optical feed cable is connected to the target device. When the optical feeder cable is not connected or is cut, the light source device stops the optical output to the TxIF by controlling the optical switch or the light source module, as shown in S10. The operation of S10 is necessary from the viewpoint of safety, since high-intensity light is output from the TxIF. Once it is confirmed that the optical fiber cable is connected, the target device requests the necessary optical fiber information from the light source device (Laser Source Request) as shown in S2. The optical fiber information includes intensity, wavelength, number of channels, channel mapping, reliability level, etc. The light source device determines whether it can satisfy the request as shown in S3. If it can satisfy the request in S2, it configures the light source module and the optical switch as shown in S4. The light source device notifies the target device that it can successfully satisfy the request as shown in S5.

[0068] As shown in S6, after the target device starts supplying light, it can request the light source device to fine-tune the light supply (intensity, wavelength, etc.), i.e., to calibrate it (Laser Source Calibration Request). This is necessary to maximize the performance of the light engine in the target device and provide optimal light supply. The light source device performs calibration as shown in S7 and reports the success of the calibration to the target device as shown in S8. Thereafter, the light source device starts supplying light as shown in S9. If the request cannot be satisfied in S3, the light source device notifies the target device that the request has failed, as shown in S11, since the request cannot be met.

[0069] The exchange of light supply information required for the light source device in the above-described control protocol facilitates confirmation of whether an appropriate light source module is being used for either the DR or FR system. The light source device disclosed herein can also use a mixture of DR and FR light source modules. The processor of the light source device can obtain information on the wavelength assignment of the light source module as status information from the light source module. In the control protocol of Figure 9 described above, in S2, light supply information from the target device is requested from the light source device. For example, in an optical switch device, the light source device can be notified of the wavelength of light required for each channel. Even if the wrong type of light source module is connected to the light source device on the front panel, the light source device can immediately detect the error by receiving a failure notification in S11. The control protocol of Figure 9 can improve the quality and efficiency of light source device maintenance and operation. The above-mentioned control protocol is based on the exchange of electrical signals, and therefore uses electrical wiring 302 capable of exchanging electrical signals as the optical feed cable connecting the two devices shown in Fig. 1. However, even if the optical feed cable does not have electrical wiring, it is possible to provide a latch mechanism in the optical connector to recognize the insertion of the optical connector of the optical feed cable, and to use some protocols in a limited manner.

[0070] In the light source devices of the first to third embodiments, it has been described that the optical switch can be simplified by limiting the number and position of spare light source modules and the spare light source modules. The light source modules have been described as outputting the same wavelength on all channels. However, for a switch device that operates in the FR system, a predetermined number of different wavelengths of light are output from the light source modules. Each channel of the light source module outputs light of a predetermined wavelength.

[0071] 3(a) is based on the assumption that the switch device operates using the DR method, so the wavelengths of all channels in the spare light source module 51 are the same, and all channels can be used for hitless switching. The optical switch 102 must have a path to guide the light from the spare light source module to any input port of the optical coupler 103, and an 8x8 optical switch is required.

[0072] In the case of a switch device operating in the FR system using four wavelengths λ1, λ2, λ3, and λ4, Light of λ1, λ2, λ3, λ4, λ1, λ2, λ3, and λ4 can be used from the light source module. With this wavelength setting, if a problem is predicted with the light of λ2 on the second channel of the working light source module, only the second or sixth channel of the backup light source module can be used for hitless switching. Since the light of each channel of the backup light source module is used only for channels of the same wavelength of the working light source module, fewer paths are required in the optical SW 102. As described above, depending on the wavelength setting of the light source module, the channels of the backup light source module that can be coupled by the optical coupler 103 differ, so the configuration of the optical SW can be simplified if necessary.

[0073] Microelectromechanical systems (MEMS) optical switches can be used as optical switches. MEMS optical switches can realize all-optical switches with around 400 channels. Although MEMS optical switches are relatively expensive, they can be used in devices such as GPU clusters, where the impact of non-operation is significant and high reliability is required. [Industrial Applicability]

[0074] The present invention can be used in a light source that provides light to a device that includes a light engine. [Explanation of symbols]

[0075] 11, 20, 201-1 to 201-n Light Engine 12,203 ASICs 13 External light source 14, 111, 112, 113, 114 Optical fiber 50, 50-1 to 50-2n, 51, 51-1 to 51-n, 101 Light Source Module 100, 100-1~100-4, 1010 Light source device 102, 102-1, 102-2 optical switches 103, 103-1 to 103-n, 107 Optical coupler 104, 104-1 to 104-n Transmit interface (TxIF) 106 Optical monitor circuit 105, 205 processors 121 CMIS signal 122, 123, 221 control signals 200 Target Devices 204-1 to 204-n Receive interface (RxIF) 300, 300-1 to 300-n optical fiber cable

Claims

1. A light source device, a plurality of light source modules including a plurality of light source elements; an optical switch that selects and outputs light from a part of the light source modules that can be set as spares among the plurality of light source modules; an optical coupler that combines light from a first light source module of the plurality of light source modules and selected light from a second light source module of the portion of the light source modules; a processor that controls the optical switch and the plurality of light source modules; Equipped with The optical switch is configured to combine light from any channel of the second light source module with light from a specific channel of the first light source module. Light source device.

2. The light source device of claim 1 , wherein the processor is configured to control the first light source module to gradually decrease the light output level and the second light source module to gradually increase the light output level in synchronization with the decrease.

3. 2. The light source device of claim 1, wherein the processor is configured to control the first light source module to stop outputting light for the specific channel and the second light source module to start outputting light for the selected channel based on status information of the light source elements from the plurality of light source modules.

4. further comprising an optical monitor circuit for measuring the level of output light from the plurality of light source modules; 2. The light source device according to claim 1, wherein the optical switch is configured to be able to set a path for providing the output light from the plurality of light source modules to the optical monitor circuit.

5. a second optical coupler that branches the output light from the optical coupler; an optical monitor circuit for measuring the level of branched light from the second optical coupler; Furthermore, The light source device according to claim 3 , wherein the processor controls the first light source module and the second light source module further based on an electrical signal from the light monitor circuit.

6. The light source device according to claim 1 , wherein the plurality of light source modules are light sources of an EPS type or an EPLSP type.

7. 10. The light source device of claim 1, which provides multiple light sources to a device including an optical transceiver in a co-packaged optics (CPO) configuration.

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