Optical Switches and Switching Systems

Abstract

The optical switch (10) of the present invention comprises a multimode waveguide section (11), a first input port (12), a second input port (13), a first output port (14), and a second output port (15), and the multimode waveguide section is configured such that a first electric field is applied to the first input port, a second electric field is applied to the second input port, and an optical output signal is output from the first output port under the condition that the phase of the first electric field leads the phase of the second electric field by 90 degrees, a third electric field is applied to the first input port, and a fourth electric field is applied to the second input port, and the phase of the combined electric field of the first electric field and the third electric field is delayed by 90 degrees with respect to the phase of the combined electric field of the second electric field and the fourth electric field, and the optical output signal is output from the second output port. As a result, the present invention can provide an optical switch that can reduce latency and power consumption.

Description

[Technical Field]

[0001] The present invention relates to an optical switch and a switching system having a multimode interferometer (MMI) structure. [Background technology]

[0002] In recent years, advances in AI and machine learning have led to an increase in the amount of data processed by computers. As a result, there has been interest in new computer architectures to improve computer processing power.

[0003] This computer architecture requires specialized processors (hereinafter referred to as "hosts") with different functions that can process a variety of workloads, and the hosts and peripheral devices must be efficiently interconnected. For example, the specialized processors may be central processing units (CPUs), graphics processing units (GPUs), field programmable gate arrays (FPGAs), etc. A switching system (interconnection structure) is also required to enable this interconnection. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] J. Dean, "1.1 The Deep Learning Revolution and Its Implications for Computer Architecture and Chip Design," 2020 IEEE International Solid-State Circuits Conference (ISSCC), 2020, pp.8-14, doi: 10.1109 / ISSCC19947.2020.9063049. Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned switching system (interconnection structure), it is necessary to reduce the latency of data transmission between hosts and reduce power consumption.

[0006] In addition, it is necessary to be able to expand the number of hosts and the bandwidth per host, that is, to have high scalability.

[0007] Furthermore, in executing functions in a switching system, it is necessary to be able to effectively utilize hosts and peripheral devices, that is, to have high utilization efficiency of computing resources. [Means for solving the problem]

[0008] In order to solve the above-described problems, an optical switch according to the present invention includes a multimode waveguide section, a first input port connected to an input side of the multimode waveguide section, a second input port connected to the input side of the multimode waveguide section in parallel with the first input port, a first output port connected to an output side of the multimode waveguide section, and a second output port connected to the output side of the multimode waveguide section in parallel with the first output port, wherein the multimode waveguide section receives a first coherent optical signal having a first electric field at the first input port and a second coherent optical signal having a second electric field at the second input port. and an optical output signal is output from the first output port under the condition that a second coherent optical signal having a third electric field is input to the first input port and a fourth coherent optical signal having a fourth electric field is input to the second input port, the phase of the combined electric field of the first electric field and the third electric field is delayed by 90 degrees relative to the phase of the combined electric field of the second electric field and the fourth electric field, and the optical output signal is output from the second output port.

[0009] An optical switch according to the present invention includes a first multimode waveguide section, a second multimode waveguide section connected via the first multimode waveguide section, a first connecting waveguide, and a second connecting waveguide, a first input port connected to an input side of the first multimode waveguide section, a second input port connected to the input side of the first multimode waveguide section in parallel with the first input port, a first output port connected to an output side of the second multimode waveguide section, a second output port connected to the output side of the second multimode waveguide section in parallel with the first output port, a first optical coupler arranged on the first connecting waveguide, and a second optical coupler arranged on the second connecting waveguide, and the first multimode waveguide section and the second multimode waveguide section are configured to receive coherent light of a predetermined wavelength at the first input port. an optical signal is input, the coherent optical signal having a first electric field is propagated through the first connecting waveguide, the coherent optical signal having a second electric field is propagated through the second connecting waveguide, and an optical output signal is output from the first output port under the condition that the phase of the first electric field leads the phase of the second electric field by 90 degrees; a third coherent optical signal having the predetermined wavelength and a third electric field is input to the first optical coupler, and a fourth coherent optical signal having the predetermined wavelength and a fourth electric field is input to the second optical coupler; the phase of the combined electric field of the first electric field and the third electric field is delayed by 90 degrees relative to the phase of the combined electric field of the second electric field and the fourth electric field; and the optical output signal of the predetermined wavelength is selected and output from the second output port. [Effects of the Invention]

[0010] According to the present invention, an optical switch and a switching system that can reduce latency and power consumption can be provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an optical switch according to a first embodiment of the present invention. [Figure 2A]FIG. 2A is a diagram illustrating the operation of the optical switch according to the first embodiment of the present invention. [Figure 2B] FIG. 2B is a diagram illustrating the operation of the optical switch according to the first embodiment of the present invention. [Figure 2C] FIG. 2C is a diagram illustrating the operation of the optical switch according to the first embodiment of the present invention. [Figure 3A] FIG. 3A is a diagram illustrating the operation of the optical switch according to the first embodiment of the present invention. [Figure 3B] FIG. 3B is a diagram illustrating the operation of the optical switch according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram illustrating the operation of the optical switch according to the first embodiment of the present invention. [Figure 5A] FIG. 5A is a schematic diagram showing the configuration of an optical switch according to a first embodiment of the present invention. [Figure 5B] FIG. 5B is a diagram for explaining the operation of the optical switch according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing the configuration of an optical switch according to the second embodiment of the present invention. [Figure 7] FIG. 7 is a diagram for explaining the effect of the optical switch according to the second embodiment of the present invention. [Figure 8] FIG. 8 is a schematic diagram showing the configuration of an optical switch according to a second embodiment of the present invention. [Figure 9] FIG. 9 is a schematic diagram showing the configuration of an optical switch according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram showing an example of the configuration of an optical switch according to the third embodiment of the present invention. [Figure 11] FIG. 11 is a schematic diagram showing an example of the configuration of an optical switch according to the third embodiment of the present invention. [Figure 12] FIG. 12 is a schematic diagram showing the configuration of a switching system according to the third embodiment of the present invention. [Figure 13]FIG. 13 is a schematic diagram showing an example of the configuration of a switching system according to the third embodiment of the present invention. [Figure 14] FIG. 14 is a schematic diagram showing the configuration of a switching system according to the fourth embodiment of the present invention. [Figure 15A] FIG. 15A is a diagram for explaining the effect of the optical switch according to the fourth embodiment of the present invention. [Figure 15B] FIG. 15B is a diagram for explaining the effect of the optical switch according to the fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] First Embodiment An optical switch according to a first embodiment of the present invention will be described with reference to FIGS.

[0013] <Optical switch configuration> As an example of the basic configuration of an optical switch 10 according to this embodiment, a 2x2 MMI using a multimode interferometer (MMI) is shown. As shown in Fig. 1, in the optical switch 10, a first input port 12 and a second input port 13 are connected as input ports to a multimode waveguide section (MMI section) 11, and a first output port 14 and a second output port 15 are connected as output ports.

[0014] The size of the multimode waveguide portion 11 is set so as to enable the operation described below. For example, the length of the multimode waveguide portion 11 is about 950 μm, and the width is about 20 μm.

[0015] <Operation of optical switching structure> The switching device operates based on the self-imaging property of the MMI (LB Soldano and ECM Pennings, "Optical multi-mode interference devices based on self-imaging: principles and applications," in Journal of Lightwave Technology, vol. 13, no. 4, pp. 615-627, April 1995.) Figures 2A-C show the relationship between the phase of the input electric field and the corresponding signal output port in a 2x2 MMI.

[0016] The electric field E1 (first electric field) and the electric field E2 (second electric field) are coherent electric fields of the same light source input to the first input port 12 and the second input port 13 of the MMI, respectively. In other words, an optical signal having the electric field E1 is coherent with an optical signal having the electric field E2.

[0017] In the first scenario, the phase of E1 leads the phase of E2 by 90 degrees, and the optical signal therefore exits from the first output port (hereinafter referred to as the "Thru port") 14 of the MMI (FIG. 2A, arrow 1 in the figure).

[0018] In the second scenario, the phase of E1 is delayed by 90 degrees relative to the phase of E2, and the optical signal therefore exits from the second output port (hereinafter referred to as the "Drop port") 15 of the MMI (Figure 2B, arrow 2 in the figure).

[0019] In the third scenario, which is 180 degrees different from E1 and E2, the optical signal is scattered within the MMI and does not exit from any output port except for a negligible amount of leakage light (Fig. 2C).

[0020] The basic operation of optical switch 10 according to this embodiment will be described with reference to Figures 3A to 4. First, a case where electric fields E1 and E2 input to the MMI have constant intensity, i.e., a case where they are not modulated, will be described.

[0021] In the initial setting before switching, as shown in FIG. 3A, the optical signal is output from the Thru port 14 of the MMI under the condition that E1 leads E2 in phase by 90 degrees (arrow 1 in the figure).

[0022] Here, the electric field E 1pls When a third electric field, E, is input to the first input port 12 of the MMI in addition to the electric field E, as shown in FIG. 3B, E 1pls The phase and magnitude of E1 and E 1pls The combined electric field resulting from the sum of 1total is selected to be

[0023] At the same time, the electric field E 2pls When a fourth electric field, E (fourth electric field), is input to the second input port 13 of the MMI in addition to the electric field E2, as shown in FIG. 3B, E 2pls The phase and magnitude of E2 and E 2pls The combined electric field resulting from the sum of 2total is selected to be

[0024] Here, the electric field E 1pls and electric field E 2pls is coherent with the electric fields E1 and E2.

[0025] As a result, the electric field E 1total is the electric field E 2total The output signal is delayed by 90 degrees in phase with respect to the input signal, and is output from the Drop port 15 of the MMI (arrow 2 in the figure).

[0026] Thus, the switching process occurs due to the electric field E 1pls and E 2pls , and the optical signal is switched from the Thru port 14 to the Drop port 15 of the MMI.

[0027] In this way, the optical switch 10 operates on unmodulated optical signals (E1, E2).

[0028] Next, we will explain the case where the electric fields E1 and E2 input to the MMI are modulated, similar to actual switching. Here, the electric fields E1 and E2 are part of the same intensity-modulated optical signal, and the electric field E 1pls and E 2pls The electric fields E1 and E2 are formed with a constant intensity without being modulated by the same light source. The operation of the optical switch 10 for optically modulated signals will now be described.

[0029] As shown in FIG. 4, in optical switch 10, when electric fields E1 and E2 are at their maximum intensity, E 1pls and E 2pls When an electric field E 1total is the electric field E 2total The optical signal is delayed in phase by 90 degrees relative to the received signal, and output from the Drop port 15 of the MMI (101 in the figure).

[0030] On the other hand, when the electric fields E1 and E2 are at their lowest intensity (zero), E 1pls and E 2pls When an electric field E 1total and electric field E 2total A phase difference of 180 degrees occurs, and the optical signal is not output from the MMI port (102 in the figure).

[0031] Thus, for a maximum level of input, a maximum level of output (dropped) signal is obtained, while for a minimum level, a minimum level of output (dropped) signal is obtained.

[0032] This allows the switching process to be performed directly on binary intensity-modulated optical signals.

[0033] Furthermore, the switching process using this optical switch 10 can be performed on multi-level signals, where it is necessary to have equal spacing between the multi-levels at the receiving end to reduce reception errors.

[0034] For example, if a transmitter transmits a signal with equally spaced levels, the intervals between the levels of the signal will no longer be equal due to switching. Therefore, the intervals between the levels are corrected by calibrating the levels of the transmitted signal in advance on the transmitting side so that the intervals between the levels will be equal when the signal is dropped (received) at the desired destination port.

[0035] As described above, in the optical switch 10 according to the present embodiment, the multimode waveguide section 11 is configured such that a first coherent optical signal having a first electric field E1 is input to the first input port 12, a second coherent optical signal having a second electric field E2 is input to the second input port 13, and an optical output signal is output from the first output port 14 under the condition that the phase of the first electric field E1 leads the phase of the second electric field E2 by 90 degrees.

[0036] A third electric field E is applied to each of the first input port 12 and the second input port 13 of the optical switch 10 having this configuration. 1pls and the fourth electric field E 2pls is applied. Here, the third electric field E 1pls and the fourth electric field E 2pls are the first electric field E1 and the third electric field E 1pls The combined electric field E 1total The phase of the second electric field E2 and the fourth electric field E 2pls The combined electric field E 2total The phase is set to be delayed by 90 degrees relative to the phase of the

[0037] As a result, an optical output signal is output from the second output port 15 .

[0038] The optical switch according to this embodiment can perform optical switching at high speed, and can reduce latency and power consumption.

[0039] <First Example> An optical switch according to a first embodiment of the present invention will be described with reference to Figures 5A and 5B. The optical switch 20 of this embodiment is used as a switching element / passive coupler in an interconnection optical bus.

[0040] <Optical switch configuration> As shown in FIG. 5A, the optical switch 20 of this embodiment has the configuration of an all-passive Mach-Zehnder interferometer (MZI), and is composed of a 1x2 MMI splitter and a 2x1 MMI coupler that function as the input stage and the output stage, respectively.

[0041] In detail, the first multimode waveguide section 21 functions as a 1x2 MMI splitter (input MMI), and the second multimode waveguide section 22 functions as a 2x1 MMI coupler (output MMI).

[0042] In other words, the optical switch 20 has a configuration in which another 2x2 MMI is provided in the upstream (input side) of the optical switch according to the first embodiment.

[0043] A first input port 23 and a second input port 24 are connected to the first multimode waveguide portion 21 as input ports.

[0044] A first output port (Thru port) 27 and a second output port (Drop port) 28 are connected to the second multimode waveguide portion 22 as output ports.

[0045] The first multimode waveguide portion 21 and the second multimode waveguide portion 22 are connected by a first connecting waveguide 25 and a second connecting waveguide 26 .

[0046] A first optical coupler 291 and a second optical coupler 292 are attached to a first connecting waveguide 25 and a second connecting waveguide 26, respectively, which connect the input and output of the MMI, and an external optical signal can be applied thereto.

[0047] As shown in FIG. 5A, in default operation, the multiplexed optical signal 3 enters the first input port 23 .

[0048] The optical signal 3 passes through the first multimode waveguide section 21 and is split, so that a first optical signal having a wavelength-multiplexed first electric field E1 and a second optical signal having a wavelength-multiplexed second electric field E2 propagate through the first connecting waveguide 25 and the second connecting waveguide 26. Here, the first electric field and the second electric field are coherent, and the phase of the first electric field E1 leads the phase of the second electric field E2 by 90 degrees.

[0049] At this time, the optical output signal 4 is output from the Thru port (first output port) 27 of the second multi-mode waveguide portion 22.

[0050] In the optical switch 20 in the above-described initial setting, as shown in FIG. 5B, a third optical signal and a fourth optical signal are input via optical couplers 291 and 292, respectively. Here, the third optical signal has a predetermined wavelength and generates an electric field E 1pls (third electric field). The fourth optical signal has the same wavelength as the third optical signal and has an electric field E 2pls (fourth electric field). The third electric field and the fourth electric field are coherent with the first electric field and the second electric field.

[0051] At this time, the first electric field E1 and the third electric field E 1pls The combined electric field E 1total The phase of the second electric field E2 and the fourth electric field E 2pls The combined electric field E 2total The phase is delayed by 90 degrees.

[0052] As a result, only the optical signal 4_1 having the same wavelength as the third and fourth optical signals is switched (selected) and output via the Drop port (second output port) 28 of the second multimode waveguide portion 22.

[0053] The optical signals 4_2 of other wavelengths are output from a Thru port (first output port) 27.

[0054] An optical switch (MZI-based device) 20 is arranged at each input / output port of the optical bus. The wavelength-multiplexed optical signal propagates along the optical bus through the same number of optical switches 20 as the number of input / output ports of the optical bus.

[0055] Electric field E 1pls and E 2pls is optically coherent with the input optical signal of the same wavelength and is switched with a high attenuation factor.

[0056] At this time, the optical signals 2_2 of other wavelengths are not affected and are output from the Thru port (first output port) 27 of the second multimode waveguide portion 22. As a result, they continue to propagate along the bus.

[0057] Also, the speed of the switching (filtering) process is determined by the electric field E 1pls and E 2pls The filtering process can be sped up because it is limited only by the application time of , which solves the problems of high-speed tunable optical filters: speed limit, wavelength drift, and bandwidth mismatch.

[0058] Connecting a large number of optical switches (MZI-based devices) 20 is necessary for scaling up the number of ports in an optical switching system. In this regard, all-fiber-based MZIs with an insertion loss of 0.3 dB are commercially available. Based on similar implementations, structures with tens of ports can be realized with reasonable power budgets.

[0059] As described above, in the optical switch 20 according to the present embodiment, the first multimode waveguide portion 21 and the second multimode waveguide portion 22 are configured such that a coherent optical signal of a predetermined wavelength is input to the first input port 23, a coherent optical signal having a first electric field E1 is propagated through the first connecting waveguide 25, a coherent optical signal having a second electric field E2 is propagated through the second connecting waveguide 26, and an optical output signal is output from the first output port 27 under the condition that the phase of the first electric field E1 leads the phase of the second electric field E2 by 90 degrees.

[0060] The first optical coupler 291 and the second optical coupler 292 of the optical switch 20 having this configuration each have a predetermined wavelength and a third electric field E 1pls a third coherent optical signal having a wavelength equal to that of the third optical signal and a fourth electric field E 2pls A fourth coherent optical signal having a third electric field E 1pls and the fourth electric field E 2pls are the first electric field E1 and the third electric field E 1pls The combined electric field E 1total The phase of the second electric field E2 and the fourth electric field E 2pls The combined electric field E 2total The phase is set to be delayed by 90 degrees relative to the phase of the

[0061] As a result, an optical output signal having the same wavelength as the third optical signal and the fourth optical signal is selected and output from the second output port 28.

[0062] The optical switch according to this embodiment can perform high-speed optical switching (filtering), reduce latency and power consumption, and is compatible with functional chains (described later), provides end-to-end optical connections, and has scalability in the number of ports.

[0063] <Second embodiment> A switching system according to a second embodiment of the present invention will be described with reference to FIGS.

[0064] <Switching system configuration> In a switching system 30 according to this embodiment, as shown in FIG. 6, a plurality of hosts 32 are connected to an optical bus 31 via a switch element 33 (for example, the optical switch according to the first embodiment).

[0065] Thus, in the switching system 30, an optical bus 31 having multiple input / output ports is shared by multiple hosts 32, and an optical switch 33 is assigned to each host 32. Also, different wavelengths are used for optical packets to avoid contention in the connections being processed.

[0066] An optical circuit is configured between two hosts using the appropriate wavelength. After the data transmission is completed, the optical circuit is torn down and the wavelength is set to free and applied to another optical circuit. Then, when the same two nodes are connected, a different wavelength is used based on wavelength availability.

[0067] In this way, wavelength allocation to optical packets is not fixed but is used flexibly.

[0068] The shared optical bus 31 is an optical waveguide such as an optical fiber, and optical multiplexers, optical switch elements, etc. are connected to the respective ports.

[0069] Data flows are transmitted over optical circuits between a source host (input port) and a destination host (output port). Optical signals from the source host join the optical bus via passive couplers.

[0070] The switching element 33 corresponding to the port of the destination host drops this signal (selects the optical signal at the desired wavelength). Here, the initial setting of the switching element 33 is to bypass all input wavelengths without dropping them.

[0071] The scalability of an optical switching system is evaluated in terms of the number of ports, bandwidth per port, and the maximum number of simultaneous connections. Here, if the number of optical wavelengths is M and the number of optical hosts is N, where N is 2 x M or more, the maximum number of optical circuits that can be configured simultaneously is M, and 2M nodes are interconnected. New connections beyond 2M cannot be made until a wavelength is initially set as free.

[0072] Here, the number of ports in the optical switching system is mainly limited by the insertion loss of the switching element 33, which is determined by the trade-off with the speed of the switching element.

[0073] Also, the bandwidth per port is limited in electrical switches by the capacity of the transceiver rather than the switching capacity of the optical switching fabric: the energy used in the optical circuit is independent of the transmitted bandwidth, and an increase in bandwidth requires a decrease in the switching energy per bit.

[0074] <Effects> As shown in Figure 7, in a configuration in which separate light sources (lasers) 34 are assigned to each host 32, the light sources are placed close to the hosts, which exhibit high temperature fluctuations, and additional circuitry is required for temperature and wavelength stabilization. This complicates implementation and increases costs. Furthermore, wavelength-tunable light sources have difficulties with wavelength tuning speed, mode hopping, and stabilization.

[0075] According to the switching system of this embodiment, the multi-wavelength light source is shared between hosts, so wavelength can be tuned at high speed, mode hopping can be suppressed, and operation can be stabilized.

[0076] Furthermore, the optical switching system can operate at switching speeds on the order of nanoseconds, and can mitigate the trade-off between insertion loss and switching element speed to match the desired number of ports (approximately 10 to 100).

[0077] The switching system according to this embodiment enables high-speed optical switching (filtering) operations, reduces latency and power consumption, and improves the scalability of the number of ports.

[0078] <Second Example> A switching system according to a second embodiment of the present invention will be described with reference to FIG.

[0079] <Switching system configuration> As shown in FIG. 8, the switching system 40 according to this embodiment includes a light source device 44, a plurality of hosts (421, 422, etc.), an optical multiplexer 431, an optical switch 432, and an optical bus 41.

[0080] The light source device 44 includes a multi-wavelength light source 441 and a 1×N wavelength selection switch (WSS) 45.

[0081] A modulator 46 is connected to a host (hereinafter referred to as the "transmitting host") 421 that transmits a data signal. The modulator 46 modulates light from a light source device 44 and converts it into a data signal. The data signal propagates through the optical bus 41 via an optical multiplexer 431. A passive optical coupler is used for the optical multiplexer 431.

[0082] A phase shifter 47, an attenuator 48, and a receiver 49 are connected to a host (hereinafter referred to as a "destination host") 422 where the data signal is to be dropped.

[0083] A data signal propagating through the optical bus 41 is selected by the optical switch 432 and dropped to the destination host 422. Here, the optical switch 432 may be, for example, the optical switch according to the first embodiment.

[0084] Here, in the destination host 422, the electric field E 1pls and E 2pls This electric field E 1pls and E 2pls is applied to the optical switch 432, causing the selected data signal to be dropped, and is received by the receiver 49 and converted to an electrical signal.

[0085] <Switching system operation> The light source device 44 in the switching system 40 includes a control unit (not shown), which includes an arbitration unit. The arbitration unit assigns a desired wavelength and identifies a desired sending host (source port) 421 and a destination host (destination port) 422. The optical signal output of the laser with the assigned wavelength is split into two parts and transmitted to the desired sending host 421 and destination host 422. In this way, the optical carrier (unmodulated optical signal) is shared between the sending host 421 and the destination host 422.

[0086] Optical signal parts entering source host 421 are modulated with electrical data generated by host 421 and transmitted along optical bus 41 towards destination host 422 .

[0087] The optical signal part input to the destination host 422 is used to select the modulated signal input from the source host 421 on the optical bus 41 and drop the optical signal part to the destination host 422 for reception. Here, the filtering method using coherent light is the same as in the first embodiment.

[0088] At the source host 421, the modulated signal is split into E1 and E2 parts and input through an MZI-based passive coupler 431. By maintaining a 90-degree phase relationship between the two input fields E1 and E2, the modulated signal exits the Thru port of the MMI output and continues propagating along the optical bus 41.

[0089] Here, for example, the optical switch according to the first embodiment may be used for the optical multiplexer 431.

[0090] In this embodiment, wavelength division is performed using a 1xN wavelength selective switch (WSS) 45. The output from the multi-wavelength light source 441 is fed to the input of the WSS 45, and each output port of the WSS 45 is directly connected to a separate (separate) host.

[0091] The arbitration unit controls the WSS 45 and provides a shared wavelength to the connecting source host 421 and destination host 422. Here, the arbitration process for multiple switching steps of a data set is performed only at the beginning, reducing overhead time. Also, wavelengths are prepared at the head of each step. Here, the data set may be processed using a function chain (described below).

[0092] For hosts arranged in a one-dimensional configuration, a ring topology can be used only when the optical signal is completely dropped at the destination node, i.e., when the signal is attenuated 100% at the thru port. Otherwise, part of this signal will continue to rotate around the ring, interfering with newly transmitted data and preventing accurate data transmission and reception. Since it is difficult to completely attenuate the optical signal, the ring is cut somewhere to make it more practical.

[0093] Therefore, to enable full connectivity among all nodes, the optical buses 41 are used in opposite directions for each transmitted data, for example, a first bus is used for transmitting data in one direction (from left to right in the figure) and a second bus is used for transmitting data in the other direction (from right to left in the figure).

[0094] In this way, in the switching system according to this embodiment, a switching operation is performed on light of a predetermined wavelength.

[0095] Therefore, by configuring a plurality of hosts to correspond to different predetermined wavelengths, it is possible to perform switching operations for light of a plurality of wavelengths.

[0096] The switching system according to this embodiment enables high-speed optical switching (filtering) operation, reducing latency and power consumption. It also improves the scalability of the number of ports. Furthermore, since a multi-wavelength light source is shared between hosts, it enables high-speed wavelength tuning, suppresses mode hopping, and stabilizes operation.

[0097] <Third Example> A switching system according to a third embodiment of the present invention will be described with reference to FIGS.

[0098] <Switching system configuration> 9, a switching system 50 according to this embodiment includes a light source device 54, a plurality of hosts 52_1 to 52_N, an optical multiplexer (e.g., 53_N), a monolithic integrated circuit 56, and an optical bus 51. Here, MZI base devices 57_1 to 57_1N (including 57_Q) serving as optical switches are integrated in the monolithic integrated circuit 56. Furthermore, a phase shifter (not shown), an attenuator (not shown), and a receiver (not shown) are integrated in each of the MZI base devices 57_1 to 57_1N. Furthermore, the light source device 54 includes a multi-wavelength light source 541 and a 1x2N-WSS 55.

[0099] In the light source device 54 in the switching system 50, the optical signal provided by a control unit (not shown) is split into two parts (not necessarily equal): the first part is provided to a source host (e.g., 52_1) and the second part is provided to an MZI-based device (e.g., 57_Q).

[0100] Here, the MZI-based devices 57_1 to 57_N function as destination hosts and are arranged in the integrated circuit 56.

[0101] In this embodiment, as shown in Figure 9, an optical signal is transmitted from one output port of the 1x2N-WSS 55 to a host itself (e.g., 52_1) functioning as a source host, and from the other output port to an MZI-based device (e.g., 57_Q) functioning as a destination host.

[0102] For example, an optical signal is transmitted to a source (transmitting) host 52_1 and an MZI-based device MZI 57_Q corresponding to a destination host 52_Q, where the MZI 57_Q functions as a switching device for the destination host 52_Q.

[0103] The optical signal parts input to the source host 52_1 are modulated by a modulator (not shown) located in the host 52_1 to generate respective optical signals having electric fields E1 and E2, which propagate along the shared optical bus 51 and input to the monolithic integrated circuit 56.

[0104] Using the optical signal part input to MZI57_Q, the electric field E 1pls and E 2pls These electric fields E 1pls and E 2pls The MZI-based device 52_Q selects a predetermined optical signal from the modulated signal (signal having electric fields E1 and E2) input from the source host 52_1 using the optical signals having electric fields E1 and E2. The selected optical signal is then dropped, received by a receiver, and transmitted to the destination host 52_Q.

[0105] As a result, the modulated signal selected for destination host 52_Q is dropped.

[0106] 10, a 1xN WSS 551 may be used as the optical signal transmitting section. In this configuration, two optical signal parts from the output port of the WSS 551 are switched by an optical splitter 58 to a source host (e.g., 52_1) and an MZI-based device (corresponding to a destination host) (e.g., 57_Q), and are then assigned to the respective hosts.

[0107] 10, by switching the optical path using an optical splitter 58, one part is sent to the source host 52_1 and the other part is sent to an MZI 57_Q corresponding to a destination host 52_Q. Other operations are the same as those in the configuration based on the 1x2N WSS described above.

[0108] 11, an Nx1 optical coupler 57 may be mounted on an integrated circuit 56. To the optical coupler 57, outputs of all N hosts 52_1 to 52_N are connected.

[0109] In the configuration of switching system 50, 50_1, the optical modulated signal is collected from the source host and fed to the input waveguide of the integrated circuit. For example, in a configuration using an optical bus with an optical coupler for each host, the distance between the source host and the integrated circuit along the shared optical bus varies from host to host, resulting in delay and loss of the optical signal.

[0110] On the other hand, with this configuration, the Nx1 optical coupler 57 is configured as part of the integrated circuit 56, and the integrated circuit 56 itself is placed at approximately the same distance from all the hosts 52_1 to 52_N, so that delay and loss of the optical signal can be suppressed.

[0111] In the switching system according to this embodiment, similar to the second embodiment, multiple hosts and multiple MZI-based devices are configured to correspond to different predetermined wavelengths, thereby enabling switching operations to be performed on light of multiple wavelengths.

[0112] <Effects> The optical switching structure of this embodiment uses a monolithic integrated circuit, allowing the number of ports in the optical switching structure to be increased by multicasting and high-speed switching (filtering), for example, to approximately 100 ports, compared to the limited scalability of cascading switching elements in only one dimension.

[0113] Also, all optical waveguides are monolithically integrated, improving signal stability, coupling into small spaces, and providing high levels of control in terms of temperature, polarization, vibration, etc.

[0114] Furthermore, there is no need for long optical buses or multiplexed buses for each propagation direction.

[0115] It also enables high-speed optical switching (filtering), reduces latency and power consumption, and improves scalability in the number of ports. Furthermore, because a multi-wavelength light source is shared between hosts, it enables high-speed wavelength tuning, suppresses mode hopping, and stabilizes operation.

[0116] <Third embodiment> A switching system (optical interconnection structure) according to a third embodiment of the present invention will be described with reference to FIGS.

[0117] <Switching system configuration> In the switching system (optical interconnection structure) according to this embodiment, for example, in the optical interconnection structure using the optical switch according to the first embodiment, a functional chain is formed.

[0118] In a function chain, different dedicated hosts are assigned to execute the functions that best suit them. Different functions can be executed in any order, with the corresponding hosts being used in the same order.

[0119] FIG. 12 shows an example of the configuration of a functional chain in a switching system (optical interconnection structure).

[0120] The switching system 60 includes an optical switch 61, an arbitration unit 64, an input / output interface unit 63, and a plurality of dedicated hosts (processors) 621-624.

[0121] Each dedicated host has a GPU #1 (621), a GPU #2 (624), an FPGA #1 (622), and an FPGA #2 (623) as functions.

[0122] For example, the input data flow is processed by each dedicated host from the interface unit 63 in the following sequence (indicated by the arrows in the figure): GPU #1 (621), then FPGA #1 (622), then GPU #2 (624), then FPGA #2 (623).

[0123] The data flow is sent through the optical switch 61 and arrives at the next host after completing each processing function.

[0124] The arbitration unit 64 sets up the optical circuits along which the data flows propagate in the optical switch 61 .

[0125] In conventional switching system control, arbitration is performed after the completion of each processing function, adding up the cumulative overhead time.

[0126] On the other hand, in the switching system 60, the functions, sequences, and elapsed times of the computers are all notified in advance, so arbitration can be performed for all switching processing steps once at the start of the processing chain, i.e., at the start of data flow reception, etc. This reduces overhead time.

[0127] <Effects> In traditional host connections, the output of each host is wired to the input of the host of the next function. However, not all hosts are used to execute the function for each input data set. As a result, this configuration does not utilize all hosts effectively, resulting in resource fragmentation.

[0128] In a switching system, resource fragmentation can be avoided by effectively interconnecting an appropriate pool of resources, such as hosts and peripherals, through a function chain. In this case, the function chain is constructed without wires, and the output of each host is switched quickly enough to the input of the next host (virtual function chain).

[0129] Furthermore, in a switching system, computing resources may be divided and configured, where the computing resources are a host (processor) and its peripheral devices.

[0130] An example of resource division is shown in Fig. 13. Computing resources of the same type, such as a CPU 71, a GPU 72, an FPGA 73, and a memory 74, are collected and arranged together on the same tray.

[0131] This configuration has the following advantages.

[0132] First, it makes it easier to maintain different hardware.

[0133] Second, it allows for rapid updates as technology advances. For example, it takes less time to upgrade memory chips compared to processor units, which are becoming more powerful. Trays of memory chips can be replaced with new versions in a plug-and-play manner, which is more practical than replacing chips within a limited server box.

[0134] Third, it allows for better resource sharing. For example, traditional memory-centric computing systems require a large pool of memory instead of continually relying on slow I / O devices. In such systems, server boxes with insufficient memory capacity limit computing performance. Also, increasing memory above average demand increases power consumption and consumes resources.

[0135] On the other hand, by dividing resources and sharing a memory pool among many processors, a large-capacity memory pool is not required, computing performance is not limited, and power consumption can be reduced.

[0136] <Fourth embodiment> A switching system (optical interconnection structure) according to a fourth embodiment of the present invention will be described with reference to FIGS. 14 to 15B.

[0137] <Switching system configuration> As shown in FIG. 14, a switching system (optical interconnection structure) 80 according to this embodiment is composed of two substrates 81 and 82 connected in parallel.

[0138] The first board 81 handles short packets, i.e., Ethernet packets or packets shorter than that. Hereinafter, it will be referred to as the "control board." This board 81 uses electrical switching, for example, an ASIC switch.

[0139] The second substrate 82 is configured with an optical switch (for example, the optical switch according to the first and second embodiments) and processes data flow. Hereinafter, it will be referred to as a "data substrate."

[0140] For example, in a switching system (optical interconnection structure) 80, as shown in Fig. 14, a control board 81 processes packets in units of packets 84, and a data board processes packets of short flows 85 and long flows 86. Here, the short flows 85 and long flows 86 are classified by the size of the data flows.

[0141] The short flow 85 has a data size equivalent to 10 Ethernet packets when transmitted at 100 Gb / s, with transition times on the order of microseconds.

[0142] Also, the long flow 86 has a data size equivalent to 100 Ethernet packets when transmitted at 100 Gb / s, with a transition time of several tens of microseconds.

[0143] <Effects> In traditional interconnect structures, increased data flow results in a larger number of packets, which increases the probability of packet collisions, resulting in increased latency.

[0144] In a configuration where virtual circuits are placed on the ASIC switch, packet collisions can be avoided, but power consumption increases. Also, the bandwidth of the OE input and output interfaces of the large-capacity ASIC switch reduces processing capacity.

[0145] As an example of a switching system (optical interconnection structure), a hybrid OE switching structure can be considered, as shown in Figure 15A. In this structure, hosts 923 are divided into groups, and hosts in the same group are interconnected to low-radix ASIC switches 922. Optical switches 921 are used to interconnect all the switches.

[0146] This structure can alleviate latency and chip interface issues by using a low-radix ASIC switch 922. It also allows for a low-host-count functional chain.

[0147] However, the host generates the data flow as electrical signals, which are transmitted over electrical links to the group's ASIC switches, and the energy required to transmit electrical bits increases with distance and data rate, as shown in Figure 15B.

[0148] Thus, transmitting large data flows at high data rates over electrical links results in high power consumption and a trade-off between link distance and number of hosts per group on the one hand, and link distance and transmitted data rate on the other hand.

[0149] On the other hand, according to the switching system (optical interconnection structure) of this embodiment, optical transmission using optical switches not only improves data speed and transmission distance compared to electrical transmission, but also reduces the transmission energy per bit, i.e., power consumption, for high data speeds.

[0150] Furthermore, the switching system (optical interconnection structure) of this embodiment can reduce transition times and handle a wide range of data flow sizes, i.e., it can handle data without being limited by the length of the flow, thereby improving the overall system efficiency in the optical interconnection structure.

[0151] In this embodiment, the arbitration unit may be provided on the control board.

[0152] In the embodiment of the present invention, an example has been shown in which wavelength multiplexing is used as the characteristic of light for multiplexing optical signals, but the present invention is not limited to this, and other optical characteristics such as orthogonal polarization and coding may also be used.

[0153] In the embodiments of the present invention, examples of the structure, dimensions, materials, etc. of each component in the configuration and manufacturing method of the optical switch and switching system are shown, but the present invention is not limited to these. Anything that can demonstrate the functions and effects of the optical switch and switching system can be used. [Industrial Applicability]

[0154] The present invention relates to optical switching and switching systems for switching packets, data flows, etc., and can be applied to computers and optical communication systems. [Explanation of symbols]

[0155] 10 Optical Switch 11 Multimode waveguide section 12 First input port 13 Second input port 14 First output port 15 Second output port

Claims

1. a multimode waveguide portion; a first input port connected to an input side of the multimode waveguide section; a second input port connected in parallel to the first input port to an input side of the multimode waveguide section; a first output port connected to an output side of the multimode waveguide section; a second output port connected in parallel to the first output port to an output side of the multimode waveguide section; Equipped with The multimode waveguide portion is a first coherent optical signal having a first electric field is input to the first input port; a second coherent optical signal having a second electric field is input to the second input port; an optical output signal is output from the first output port under a condition that the phase of the first electric field leads the phase of the second electric field by 90 degrees; a third coherent optical signal having a third electric field is input to the first input port; a fourth coherent optical signal having a fourth electric field is input to the second input port; delaying the phase of a composite electric field of the first electric field and the third electric field by 90 degrees with respect to the phase of a composite electric field of the second electric field and the fourth electric field; The optical output signal is output from the second output port. An optical switch characterized by:

2. the first coherent optical signal and the second coherent optical signal are multilevel signals, The intervals between the multi-level levels of the multi-level signal are set to be equal intervals between the multi-level levels when output from the second output port.

2. The optical switch according to claim 1, wherein:

3. a first multimode waveguide section; a second multimode waveguide portion connected to the first multimode waveguide portion via a first connecting waveguide and a second connecting waveguide; a first input port connected to an input side of the first multimode waveguide section; a second input port connected in parallel to the first input port to an input side of the first multimode waveguide section; a first output port connected to an output side of the second multimode waveguide section; a second output port connected in parallel to the first output port to an output side of the second multimode waveguide section; a first optical coupler disposed on the first connection waveguide; a second optical coupler disposed on the second connecting waveguide; Equipped with the first multimode waveguide portion and the second multimode waveguide portion, a coherent optical signal of a predetermined wavelength is input to the first input port; the coherent optical signal having a first electric field is propagated through the first connecting waveguide; the coherent optical signal having a second electric field is propagated through the second connecting waveguide; an optical output signal is output from the first output port under a condition that the phase of the first electric field leads the phase of the second electric field by 90 degrees; inputting a third coherent optical signal having the predetermined wavelength and a third electric field into the first optical coupler; inputting a fourth coherent optical signal having the predetermined wavelength and a fourth electric field into the second optical coupler; delaying the phase of a composite electric field of the first electric field and the third electric field by 90 degrees with respect to the phase of a composite electric field of the second electric field and the fourth electric field; The optical output signal of the predetermined wavelength is selected and output from the second output port. An optical switch characterized by:

4. at least one optical multiplexer; At least one optical switch according to claim 3; at least one transmitting host connected to the optical multiplexer; at least one destination host connected to the optical switch; a light source device; a modulator; A phaser; an attenuator; Receiver and Equipped with the light source device includes a multi-wavelength light source and a wavelength selective switch, and generates an optical signal having a predetermined wavelength; the modulator is disposed in the transmitting host and modulates one of the optical signals; the optical multiplexer multiplexes the modulated one optical signal and propagates the multiplexed signal; the phase shifter and the attenuator receive the other of the optical signals, generate optical signals having the predetermined wavelength and the third electric field and the fourth electric field, and apply the optical signals to the optical switch; The receiver receives the optical signal selected by the optical switch from the one optical signal. A switching system comprising:

5. Equipped with an optical bus, the optical multiplexer and the optical switch are each disposed on the optical bus; the light source device is connected to the sending host and the destination host; The phase shifter, the attenuator, and the receiver are located in the destination host.

5. The switching system according to claim 4.

6. The optical bus, a monolithic integrated circuit in which the optical switch, the phase shifter, the attenuator, and the receiver are integrated; the optical bus is connected to the monolithic integrated circuit; The selected optical signal is transmitted from the receiver to the destination host.

5. The switching system according to claim 4.

7. an optical splitter that splits and transmits the optical signal from the light source device to the sending host or the destination host and the optical switch; The wavelength selective switch is a 1xN wavelength selective switch.

7. The switching system according to claim 6.

8. a monolithic integrated circuit in which an optical coupler, the optical switch, the phase shifter, the attenuator, and the receiver are integrated; an output of the sending host and an output of the destination host are connected to the optical coupler; The selected optical signal is transmitted from the receiver to the destination host.

5. The switching system according to claim 4.

9. It has a mediation department, The virtual function chain is configured and arbitration is performed at the start of the receive data flow.

5. The switching system according to claim 4.

10. Computing resources are divided into groups of the same type 5. The switching system according to claim 4.

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