Nanosecond optical switch array and nanosecond wavelength selective switch

Abstract

To provide a nanosecond optical switch array or a nanosecond wavelength switch of which a switching speed is high, and the size can be easily increased.SOLUTION: In a nanosecond optical switch array switching an optical path of an optical signal, a plurality of 2i×2i input side optical switch units (i≥1), a plurality of 2j×2j central part optical switch units (j≥2), and a plurality of 2k×2k output side optical switch units (k≥1) are logically and serially arranged, an output port of each input side optical switch unit and an input port of each central part optical switch unit, and an output port of each central part optical switch unit and an input port of each output side optical switch unit are connected in accordance with a predetermined mathematical expression or a regulation. A switching speed of each input side optical switch unit, each central part optical switch unit, and each output side optical switch unit is a nanosecond order, and is controlled by being synthesized by a digital signal.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a scalable nanosecond optical switch array and a nanosecond wavelength selective switch. [Background technology]

[0002] As the computing power of a single chip (or board) has reached its limits, distributed systems such as data centers and chip clusters are being actively developed and deployed. To prevent these systems from becoming a bottleneck, optical switches and wavelength selective switches (WSSs) used in optical networks are expected to have the following features: (1) High single-lane data rates (e.g., 100 Gbps or more); (2) Ability to support ultra-large-scale networks (e.g., 1,000 or more nodes); (3) High switching speeds on the order of nanoseconds are required to improve packet / traffic delivery efficiency, since slow switching speeds result in switching times longer than packet delivery times; and (4) Adaptability to various topologies and high wavelength resource accommodation efficiency are required to accommodate complex computing graphs that meet application requirements.

[0003] MEMS (Micro Electro Mechanical Systems) is the mainstream technology for realizing large-scale optical switches, but its switching speed is on the order of microseconds (Patent Document 1). Also, WSS (wavelength selective switch) is usually implemented using LCOS (Liquid Crystal on Silicon), and its switching speed is also on the order of microseconds (Patent Document 2).

[0004] Furthermore, Patent Document 3 discloses technology for a large-scale optical switch array for data centers. Patent Document 4 or Patent Document 5 discloses technology for a crossbar-shaped optical switch array. Non-Patent Document 1 or Non-Patent Document 2 discloses technology for a nanosecond switch architecture based on an SOA (Semiconductor Optical Amplifier) ​​and an AWG (Arrayed Waveguide Grating), realizing high-speed, large-scale switching. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US20160154183A1 [Patent Document 2] US8078019B2 [Patent Document 3] US11206466B2 [Patent Document 4] US20130243372A1 [Patent Document 5] EP3555681B1 [Non-patent literature]

[0006] [Non-Patent Document 1] Joshua L. Benjamin, Thomas Gerard, Domanic Lavery, Polina Bayvel, and Georgios Zervas, "PULSE: Optical Circuit Switched Data Center Architecture Operating at Nanosecond Timescales," J. Lightwave Technol. 38, 4906-4921 (2020) [Non-patent document 2] Ballani, Hitesh, et al. "Sirius: A flat datacenter network with nanosecond optical switching." Proceedings of the Annual conference of the ACM Special Interest Group on Data Communication on the applications, technologies, architectures, and protocols for computer communication. 2020. Summary of the Invention [Problem to be solved by the invention]

[0007] The large-scale optical switch array technology for data centers in Patent Document 3 differs from the present invention in its construction method. The crossbar-shaped optical switch array technology in Patent Document 4 or Patent Document 5 differs from the present invention in its basic technology. Furthermore, the technology in Non-Patent Document 1 or Non-Patent Document 2 lacks adaptability to various topologies and wavelength resource accommodation efficiency, and it is not easy to detect configuration errors.

[0008] The present invention has been made in view of the above circumstances, and has as its object to provide a nanosecond optical switch array or nanosecond wavelength selective switch that has a high switching speed and can be easily scaled up. [Means for solving the problem]

[0009] (1) In order to achieve the above object, the present invention provides the following means. That is, a nanosecond optical switch array according to one aspect of the present invention comprises: Controlled by the controller A nanosecond optical switch array for switching the communication path of an optical signal, comprising: i ×2 i An input-side optical switch unit (i≧1) and a plurality of 2 j ×2 j A central optical switch unit (j≧2) and multiple 2 k ×2k and output-side optical switch units (k≧1), which are logically arranged in series, and the output ports of the input-side optical switch units and the input ports of the central optical switch units, and the output ports of the central optical switch units and the input ports of the output-side optical switch units are connected according to a predetermined mathematical formula or rule, and the switching speeds of the input-side optical switch units, the central optical switch units, and the output-side optical switch units are on the order of nanoseconds; The input-side optical switch unit, the central optical switch unit, and the output-side optical switch unit receive signals from the controller. It is synchronized and controlled by a digital signal.

[0010] (2) In the nanosecond optical switch array according to one embodiment of the present invention, i=j=k, and each i The input-side optical switch units, the central optical switch unit, and the output-side optical switch unit are connected together.

[0011] (3) In the nanosecond optical switch array according to one embodiment of the present invention, i=k=1, and 2 j the input side optical switch units, the two central optical switch units, and the two j The output side optical switch units are connected.

[0012] (4) Furthermore, the nanosecond optical switch array according to one embodiment of the present invention switches the communication path of an optical signal. m ×2 n A nanosecond optical switch array, m ×2 m Input side optical switch unit (m≧2) and 2 m Pieces 1×2 n-m and an output side optical switch unit (nm≧1), which are logically arranged in series, and the two m ×2 m The output port of the input optical switch unit and the 1×2 n-m The input ports of the output side optical switch unit are connected one-to-one, and the two m ×2 m Input side optical switch unit and the 1×2 n-mThe switching speed of the output optical switch unit is on the order of nanoseconds and is synchronized and controlled by a digital signal. m ×2 m The input-side optical switch unit is the nanosecond optical switch array described in (2) or (3) above. [Effects of the Invention]

[0017] According to the present invention, it is possible to configure a nanosecond optical switch array or a nanosecond wavelength selective switch that has a high switching speed and can be easily scaled up. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram of a nanosecond optical switch array according to one embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram of a 22m×22m nanosecond optical switch array according to one embodiment of the present invention. [Figure 3] 1 is an example of a flowchart of a first method. [Figure 4] 1(a) to 1(d) are schematic diagrams each showing an example of a nanosecond optical switch array. [Figure 5] FIG. 1 is a schematic diagram of a 2m+1×2m+1 nanosecond optical switch array according to one embodiment of the present invention. [Figure 6] 10 is an example of a flowchart of a second method. [Figure 7] 1(a) and 1(b) are schematic diagrams showing examples of nanosecond optical switch arrays. [Figure 8] FIG. 1 is a schematic diagram showing an example of a 16×16 nanosecond optical switch array. [Figure 9] FIG. 1 is a schematic diagram of a 1×2 m nanosecond optical switch array according to one embodiment of the present invention. [Figure 10] 1(a) to 1(c) are schematic diagrams each showing an example of a nanosecond optical switch array. [Figure 11] 1 is a schematic diagram of a 2m×2n nanosecond optical switch array according to one embodiment of the present invention. [Figure 12]FIG. 1 is a schematic diagram showing an example of a 16×64 nanosecond optical switch array. [Figure 13] 1A and 1B are schematic diagrams of a nanosecond wavelength selective switch according to one embodiment of the present invention. [Figure 14] 1 is a schematic diagram of a nanosecond wavelength selective switch according to one embodiment of the present invention; [Figure 15] FIG. 1 is a schematic diagram showing an example of a nanosecond wavelength selective switch. [Figure 16] FIG. 1 is a schematic diagram showing an example of a nanosecond wavelength selective switch. [Figure 17] FIG. 1 is a schematic diagram illustrating an example of an optical network. [Figure 18] FIG. 1 is a schematic diagram illustrating an example of an optical network. [Figure 19] FIG. 1 is a schematic diagram illustrating an example of an optical network. [Figure 20] FIG. 1 is a schematic diagram of a control plane. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are merely examples, and the present invention is not limited to the contents of the embodiments. Furthermore, in the following drawings, components that are not necessary for explaining the embodiments are omitted from the drawings. Specifically, for example, control functions and the like that are not necessary for explaining the embodiments are omitted from the drawings.

[0020] [Embodiment] (Configuration of nanosecond optical switch array) FIG. 1 is a schematic diagram of a nanosecond optical switch array according to one embodiment of the present invention. The nanosecond optical switch array according to one embodiment of the present invention switches the communication path of an optical signal. The nanosecond optical switch array has a plurality of 2 i ×2 i An input-side optical switch unit (i≧1) and a plurality of 2 j ×2 j A central optical switch unit (j≧2) and multiple 2 k ×2 kand an output-side optical switch unit (k≧1).

[0021] The input side optical switch unit, central optical switch unit, and output side optical switch unit are collectively referred to as an optical switch unit. An optical switch unit refers to an optical switch that is a component that constitutes the nanosecond optical switch array of the present invention. An optical switch unit is assumed to already have some kind of connection between the input port and the output port internally. Therefore, when the nanosecond optical switch array of the present invention is used as a component that constitutes a larger nanosecond optical switch array, it is referred to as an optical switch unit. Furthermore, the optical switch unit may be an optical switch other than the nanosecond optical switch array of the present invention.

[0022] 2 i ×2 i An optical switch unit is a unit with two input ports. i pcs, 2 output ports i It is an optical switch that can select the path of an optical signal by control from any of the input ports to any of the output ports. The same applies to j and k. In the optical switch unit of FIG. 1, the port on the left is called the input port and the port on the right is called the output port. This is also true for other figures. For convenience, in this specification, one port of the optical switch unit or nanosecond optical switch array is called the input port and the other port is called the output port, but in reality, an optical signal may be input from the output port and output from the input port.

[0023] The nanosecond optical switch array is a i ×2 i an input-side optical switch unit and a plurality of 2 j ×2 j The central optical switch unit and multiple 2 k ×2 kThe output-side optical switch units are logically arranged in series. The output ports of the input-side optical switch units and the input ports of the central optical switch units, and the output ports of the central optical switch units and the input ports of the output-side optical switch units are connected according to a predetermined mathematical formula or rule. In this way, by arranging small-scale optical switch units in series in three stages (three layers) and connecting each port regularly according to a predetermined mathematical formula or rule, a larger-scale optical switch array can be easily constructed. The predetermined mathematical formula or rule will be described later.

[0024] Some of the output ports of the input-side optical switch unit, some of the input or output ports of the central optical switch unit, or some of the input ports of the output-side optical switch unit may not be connected to other ports, provided that there is no optical switch unit in which all of the output ports of the input-side optical switch unit, all of the input or output ports of the central optical switch unit, or all of the input ports of the output-side optical switch unit are not connected to other ports.

[0025] The switching speeds of the input optical switch unit, central optical switch unit, and output optical switch unit are on the order of nanoseconds and are synchronized and controlled by digital signals. This allows the nanosecond optical switch array to operate on the order of nanoseconds. A switching speed on the order of nanoseconds means that the time required for one switching operation is less than 1 microsecond. The switching speed is preferably 100 nanoseconds or less, and more preferably 10 nanoseconds or less. A switching speed of less than 1 nanosecond is also included in the nanosecond order.

[0026] Multiple 2 i ×2 i Output ports of the input optical switch unit, j ×2 j The input and output ports of the central optical switch unit and multiple 2 k ×2 kAll input ports of the output optical switch unit are connected to other ports, m ×2 m When constructing a nanosecond optical switch array (m>i,j,k), 2 i ×2 i Two input optical switch units m-i pieces, 2 j ×2 j The central optical switch unit is m-j pieces, 2 k ×2 k Two output optical switch units m-k Prepare pieces.

[0027] And the pth 2 i ×2 i The qth output port of the input side optical switch unit is connected to the rth j ×2 j Connect to the sth input port of the central optical switch unit. Note that p, q, r, and s indicate the logical numbers of each optical switch unit or its port. When i≦j, r 2 j +s to 2 i The quotient when divided by is r', and the remainder is s', where 1≦s'≦2 i In this case, for example, it can be connected according to the given formula p=s', q=r'. Also, when i>j, p·2 i +q to 2 j The quotient when divided by is p', and the remainder is q', where 1≦q'≦2 j In this case, for example, connections can be made according to the predetermined formulas p'=s, q'=r.

[0028] Similarly, the t-th 2 j ×2 j The u-th output port of the central optical switch unit is connected to the v-th 2 k ×2 k Connect to the wth input port of the output optical switch unit. As above, t, u, v, and w indicate the logical numbers of each optical switch unit or its port. When j≦k, v 2 k +w to 2 j The quotient when divided by is v', and the remainder is w', where 1≦w'≦2j In this case, for example, it can be connected according to the predetermined formula t=w', u=v'. Also, when j>k, t·2 j +u to 2 k The quotient when divided by is t', and the remainder is u', where 1≦u'≦2 k In this case, for example, connections can be made in accordance with the predetermined formulas t'=w and u'=v.

[0029] In this way, by regularly connecting the input side optical switch unit, the central optical switch unit, and the output side optical switch unit according to a predetermined formula or rule, m ×2 m A nanosecond optical switch array can be configured. Note that the above-mentioned predetermined formulas or rules are only examples, and any formulas or rules can be used for connection as long as they allow control of the nanosecond optical switch array. For example, if there are free ports, formulas or rules that take the free ports into account can be used.

[0030] In the nanosecond optical switch array, it is preferable that i=j=k. This allows the nanosecond optical switch array to be configured with one type of optical switch unit. In this case, each of the i It is preferable that the input side optical switch units, the central optical switch unit, and the output side optical switch unit are connected, thereby forming an efficient nanosecond optical switch array using all ports.

[0031] In the nanosecond optical switch array, it is preferable that i=k=1. This makes it possible to reduce the insertion loss when the scale is increased. j 1 input optical switch unit, 2 central optical switch units, and 2 j It is preferable that output-side optical switch units are connected. This allows for the construction of an efficient nanosecond optical switch array that uses all ports. Also, it is possible to construct a nanosecond optical switch array of the required scale.

[0032] (Method for constructing nanosecond optical switch arrays) The nanosecond optical switch array of the present invention can be easily constructed into a large-scale nanosecond optical switch array by using small-scale nanosecond optical switch arrays as optical switch units and repeating the same arrangement and connection method. m ×2 m This paper describes a method for constructing (expanding) a nanosecond optical switch array of this type.

[0033] (First method) FIG. 2 is a diagram illustrating a second embodiment of the present invention. 2m ×2 2m Figure 2 shows a schematic diagram of a nanosecond optical switch array. 2m ×2 2m The first method is to use a 2 m ×2 m 3x2 optical switch units m Use 2 pieces 2m ×2 2m This is a method for constructing nanosecond optical switch arrays. i ×2 i Input side optical switch unit, 2 j ×2 j Central optical switch unit and 2 k ×2 k In the output side optical switch unit, i=j=k=m. Also, the input side optical switch unit, the central optical switch unit, and the output side optical switch unit are each divided into 2 m Prepare pieces.

[0034] Let (x, y, z, l) be a symbol indicating the position of an input port of one of the optical switch units, and (x, y, z, r) be a symbol indicating the position of an output port of one of the optical switch units, and they are defined as follows: The first value (first coordinate) is a value that identifies the optical switch unit, with 1 indicating the input-side optical switch unit, 2 indicating the central optical switch unit, and 3 indicating the output-side optical switch unit. The second value (second coordinate) is a value that indicates the order of the multiple optical switch units. The third value (third coordinate) is a value that indicates the port number of each optical switch unit. According to this definition, for example, (1, 3, 2, l) indicates the second input port of the third input-side optical switch unit. Also, for example, (2, 4, 1, r) indicates the first output port of the fourth central optical switch unit.

[0035] When defined as above, in the first method, for example, each port can be connected according to the following rule: Connect all (1,y,z,r) and (2,z,y,l), and connect all (2,y,z,r) and (3,z,y,l). (1,y,z,l) and (3,y,z,r) become the input port and output port of the nanosecond optical switch array, respectively. This allows 2 m ×2 m 3x2 optical switch units m Use 2 pieces 2m ×2 2m An optical switch unit can be constructed.

[0036] The following describes the flow of fabricating a 65,536 × 65,536 nanosecond optical switch array using 2 × 2 optical switch units by the first method. Figure 3 is an example of a flowchart of the first method. In Figure 3, optical switch units are referred to as units. Figures 4(a) to 4(d) are each a schematic diagram showing an example of a nanosecond optical switch array. First, the required number of 2 × 2 optical switch units are prepared (step S1). Next, n = 2 (step S2), and n × n optical switch units are arranged in three layers (step S3).

[0037] Next, the ports of the optical switch unit are connected (step S4). The above formulas and rules can be applied to the connection of the ports. Next, n 2 <65536, n 2 If <65536 holds (YES in step S5), proceed to step S6. 2 <65536 is not true (n 2 = 65536 is true (step S5, NO), a 65536 x 65536 nanosecond optical switch array has been fabricated, and the process ends.

[0038] In step S6, n 2 ×n 2 It is determined whether the required number of optical switch units have been produced, and if the required number have not been produced (step S6, NO), the process returns to step S3. 2 ×n 2 On the other hand, if the required number of optical switch units are produced (step S6, YES), 2 (Step S7), return to Step S3, and set n 2 ×n 2 Fabricating an optical switch unit. In this way, a 65536 × 65536 nanosecond optical switch array can be fabricated by repeating the same method using a 2 × 2 optical switch unit in the first method.

[0039] Figure 4(a) shows a 4x4 nanosecond optical switch array constructed using six 2x2 optical switch units. (1,1,1,r) and (2,1,1,l), (1,1,2,r) and (2,2,1,l), (1,2,1,r) and (2,1,2,l), and (1,2,2,r) and (2,2,2,l) are connected. The same is true for (2,y,z,r) and (3,z,y,l). The 2x2 optical switch unit, which has a switching speed on the order of nanoseconds, can use existing 2x2 optical switches.

[0040] Figure 4(b) shows a 16x16 nanosecond optical switch array constructed using twelve 4x4 optical switch units. For 1 ≤ y, z ≤ 4, all (1, y, z, r) and (2, z, y, l) are connected, and all (2, y, z, r) and (3, z, y, l) are connected. The 4x4 optical switch unit, whose switching speed is on the order of nanoseconds, can be used in the above 4x4 nanosecond optical switch array.

[0041] Figure 4(c) shows a 256 × 256 nanosecond optical switch array constructed using 48 16 × 16 optical switch units. For 1 ≦ y, z ≦ 16, all (1, y, z, r) and (2, z, y, l) are connected, and all (2, y, z, r) and (3, z, y, l) are connected. The 16 × 16 optical switch unit, whose switching speed is on the order of nanoseconds, can be used in the above 16 × 16 nanosecond optical switch array.

[0042] Figure 4(d) shows a 65536 × 65536 nanosecond optical switch array constructed using 768 256 × 256 optical switch units. For 1 ≦ y, z ≦ 256, all (1, y, z, r) and (2, z, y, l) are connected, and all (2, y, z, r) and (3, z, y, l) are connected. The 256 × 256 optical switch unit, whose switching speed is on the order of nanoseconds, can be used in the above 256 × 256 nanosecond optical switch array.

[0043] In the above explanation, the 2x2 optical switch unit is used as the minimum unit for expansion, so m ×2 m However, the first method uses n × n optical switch units to 2 ×n 2 Since it is possible to fabricate nanosecond optical switch arrays, different types of nanosecond optical switch arrays can be fabricated by using n×n optical switch units (n≠2, 4, 16, 256, ...). Also, when using an existing 2×2 optical switch, the first method requires a 65536×65536 (216 ×2 16 However, if optical switches with lower insertion loss than existing optical switches become available in the future, it may be possible to build even larger nanosecond optical switch arrays.

[0044] (Second method) FIG. 5 shows a second embodiment of the present invention. m+1 ×2 m+1 Schematic diagram of a nanosecond optical switch array. Figure 5 shows a nanosecond optical switch array configured by the second method. The second method is a 2 m ×2 m Two optical switch units (m≧2) and two 2×2 optical switch units m+1 Use 2 pieces m+1 ×2 m+1 This is a method for constructing nanosecond optical switch arrays. i ×2 i Input side optical switch unit, 2 j ×2 j Central optical switch unit and 2 k ×2 k In the output side optical switch unit, i=k=2 and j=m. Also, the input side optical switch unit and the output side optical switch unit are each 2 m Prepare one optical switch unit and two central optical switch units.

[0045] Define (x,y,z,l) and (x,y,z,r) in the same way as above. In the second method, you can connect each port according to the same rules as in the first method. To explain it again, connect all (1,y,z,r) and (2,z,y,l), and connect all (2,y,z,r) and (3,z,y,l). (1,y,z,l) and (3,y,z,r) become the input and output ports of the nanosecond optical switch array, respectively. This allows you to m ×2 m Two optical switch units and two 2x2 optical switch units m+1 Use 2 pieces m+1 ×2 m+1 Nanosecond optical switch arrays can be constructed.

[0046] The following describes the flow of fabricating a 65,536 × 65,536 nanosecond optical switch array using 2 × 2 optical switch units by the second method. Figure 6 is an example of a flowchart for the second method. In Figure 6, optical switch units are also referred to as units. Figures 7(a) and 7(b) are schematic diagrams showing an example of a nanosecond optical switch array. First, the required number of 2 × 2 optical switch units are prepared (step T1). Next, n = 2 (step T2), and n 2 × 2 optical switch units, two n × n optical switch units, and n 2 × 2 optical switch units are arranged in three layers (step T3).

[0047] Next, each port of the optical switch unit is connected (step T4). The above formulas and rules can be applied to connect the ports. Next, it is determined whether 2n<65536. If 2n<65536 holds (step T5, YES), proceed to step T6. On the other hand, if 2n<65536 does not hold (2n=65536 holds) (step T5, NO), a 65536 x 65536 nanosecond optical switch array has been created, and the process ends.

[0048] In step T6, it is determined whether two 2n x 2n optical switch units have been fabricated. If not (step T6, NO), the process returns to step T3 to fabricate a 2n x 2n optical switch unit. On the other hand, if two units have been fabricated (step T6, YES), 2n is substituted for n (step T7), and the process returns to step T3 to fabricate a 2n x 2n optical switch unit with the next value. In this way, in the second method, a 65536 x 65536 nanosecond optical switch array can be fabricated by repeating the same method using 2 x 2 optical switch units.

[0049] Figure 7(a) shows an 8x8 nanosecond optical switch array constructed using two 4x4 optical switch units and eight 2x2 optical switch units. For 1 ≤ y ≤ 4 and 1 ≤ z ≤ 2, all (1, y, z, r) and (2, z, y, l) are connected, and all (2, y, z, r) and (3, z, y, l) are connected. The 4x4 optical switch unit, which has a switching speed on the order of nanoseconds, can be used with the 4x4 nanosecond optical switch array described above. Furthermore, the 2x2 optical switch unit, which has a switching speed on the order of nanoseconds, can be used with existing 2x2 optical switches.

[0050] Figure 7(b) shows a schematic diagram of a 16x16 nanosecond optical switch array constructed using two 8x8 optical switch units and sixteen 2x2 optical switch units. For 1≦y≦8 and 1≦z≦2, all (1,y,z,r) and (2,z,y,l) are connected, and all (2,y,z,r) and (3,z,y,l) are connected. The 8x8 optical switch unit, which has a switching speed on the order of nanoseconds, can be used in the above 8x8 nanosecond optical switch array.

[0051] Figure 8 is a schematic diagram showing an example of a 16x16 nanosecond optical switch array. Figure 8 shows a 16x16 nanosecond optical switch array constructed using four 4x4 optical switch units and 32 2x2 optical switch units. In other words, it shows a nanosecond optical switch array in which the 8x8 optical switch unit in Figure 7(b) is replaced with the 4x4 optical switch unit in Figure 7(a). By comparing Figure 4(b) and Figure 8, it is clear that 2 m It can be seen that the first and second methods are different when ≧16. Note that the 4×4 nanosecond optical switch array has the same configuration in the first and second methods.

[0052] By repeating the second method, 2 m ×2 m It is possible to construct a nanosecond optical switch array (m = 2, 3, 4, ...). In the above explanation, the 2 × 2 optical switch unit is used as the minimum unit for expansion, so m ×2 mHowever, the second method can be used to fabricate a 2n × 2n nanosecond optical switch array using n × n optical switch units, so it is possible to fabricate a 2 × 2 optical switch unit and an n × n optical switch unit (n ≠ 2 m ) can be used to create different types of nanosecond optical switch arrays. When using an existing 2x2 optical switch, the second method increases the insertion loss by about 0.6 dB for each expansion, so 16 ×2 16 However, if optical switches with lower insertion loss than existing optical switches become available in the future, it may be possible to build even larger nanosecond optical switch arrays.

[0053] In the above, 2 m ×2 m We have explained how to build a nanosecond optical switch array. However, when using a nanosecond optical switch array in a nanosecond wavelength selective switch (described later) or various networks, a 1x2 n Nanosecond optical switch array and 2 m ×2 n It is desirable to be able to construct a nanosecond optical switch array (m ≠ n). Therefore, in the following, we will use a 1 × 2 n Nanosecond optical switch array and 2 m ×2 n A method for constructing a nanosecond optical switch array is described.

[0054] FIG. 9 is a 1×2 n Schematic diagram of a nanosecond optical switch array. 1×2 n The nanosecond optical switch array is a 1x2 m Input side optical switch unit (m≧1) and 2 m Pieces 1×2 n-m Equipped with an output optical switch unit (nm≧1), 1×2 m Output port of input side optical switch unit and 1×2 n-m The input ports of the output optical switch unit are connected one-to-one. 1×2 m Input side optical switch unit and 1x2 n-mThe switching speed of the output optical switch unit is on the order of nanoseconds and is synchronized and controlled by digital signals. n The nanosecond optical switch array can be operated on the order of nanoseconds.

[0055] Specific examples are shown in Figures 10(a) to 10(c). Figures 10(a) to 10(c) are schematic diagrams showing examples of nanosecond optical switch arrays. Figures 10(a) to 10(c) show a 1x4 nanosecond optical switch array 150, a 1x16 nanosecond optical switch array 160, and a 1x256 nanosecond optical switch array 170, respectively. In this way, by sequentially expanding using 1x2 optical switch units, a 1x2 n It is possible to construct a nanosecond optical switch array. In Figures 10(a) to 10(c), the input-side optical switch unit and the output-side optical switch unit are expanded as the same optical switch unit, but different optical switch units may also be used for expansion.

[0056] FIG. 11 shows a second embodiment of the present invention. m ×2 n Schematic diagram of a nanosecond optical switch array. m ×2 n Nanosecond optical switch arrays are 2 in 1 m ×2 m Input side optical switch unit (m≧1) and 2 m Pieces 1×2 n-m Equipped with an output optical switch unit (nm≧1), m ×2 m Output port of input side optical switch unit and 1×2 n-m The input ports of the output optical switch units are connected one-to-one. m ×2 m Input side optical switch unit and 1x2 n-m The switching speed of the output optical switch unit is on the order of nanoseconds and is synchronized and controlled by digital signals. m ×2 n The nanosecond optical switch array can be operated in nanosecond order. m ×2m Input side optical switch unit or 1x2 n-m The output side optical switch unit may be the nanosecond optical switch array constructed above.

[0057] A specific example is shown in FIG. 12. FIG. 12 is a schematic diagram showing an example of a 16×64 nanosecond optical switch array 180. m ×2 m Build nanosecond optical switch arrays, 1x2 if necessary n-m By constructing nanosecond optical switch arrays and combining them, m ×2 n Nanosecond optical switch arrays can be constructed.

[0058] (Configuration of nanosecond wavelength selective switch) 13(a), (b), and 14 are schematic diagrams of a nanosecond wavelength selective switch according to one embodiment of the present invention. A nanosecond wavelength selective switch 200 according to one embodiment of the present invention separates wavelength-multiplexed optical signals into predetermined wavelength ranges and switches communication paths. Note that the nanosecond wavelength selective switch may receive an optical signal input from an output port and output from an input port. Therefore, the nanosecond wavelength selective switch may wavelength-multiplex optical signals separated into predetermined wavelength ranges via different communication paths, and combine them into an optical signal with a wide wavelength range that passes through one communication path. A nanosecond wavelength selective switch has one or more input-side AWGs (Arrayed Waveguide Gratings) and multiple 2 m ×2 n It includes an optical switch unit (m≧0, n≧2) and multiple output AWGs. m ×2 n The optical switch unit is preferably the nanosecond optical switch array 100 described above.

[0059] The nanosecond wavelength selective switch 200 has one or more input side AWGs and a plurality of 2 m ×2 nAn optical switch unit and multiple output AWGs are logically arranged in series. The output port of the input AWG and the input port of the optical switch unit, and the output port of the optical switch unit and the input port of the output AWG are connected according to a predetermined formula or rule. In this way, a nanosecond wavelength selective switch can be easily constructed by arranging an AWG, an optical switch unit, and an AWG in series in three stages and connecting each port according to a predetermined formula or rule. The predetermined formula or rule will be described later.

[0060] Some of the output ports of the input AWG, some of the input or output ports of the optical switch unit, or some of the input ports of the output AWG may not be connected to other ports, but there is no AWG or optical switch unit in which all of the output ports of the input AWG, all of the input or output ports of the optical switch unit, or all of the input ports of the output AWG are not connected to other ports.

[0061] The switching speed of the optical switch unit is on the order of nanoseconds and is controlled by a digital signal, allowing the nanosecond wavelength selective switch to operate on the order of nanoseconds.

[0062] In the nanosecond wavelength selective switch, m≦n, and 2 m 2 input AWGs and n 2 optical switch units and n The output AWG is connected to the input port of the input AWG. n The output port is 2 n It is preferable that the wavelength selective switch has 1 input port and 1 output port. This allows the configuration of an efficient nanosecond wavelength selective switch that uses all ports.

[0063] In the above case, the predetermined formula or rule can be defined as follows, for example. Let (x,y,z,l) and (x,y,z,r) be defined in the same way as the nanosecond optical switch array. Connect all (1,y,z,r) to (2,z,y,l), and connect all (2,y,z,r) to (3,z,y,l). (1,y,z,l) and (3,y,z,r) become the input port and output port of the nanosecond wavelength selective switch, respectively.

[0064] In this way, by connecting the input AWG, optical switch unit, and output AWG according to a predetermined formula or rule, m ×2 n A nanosecond wavelength selective switch can be configured. Note that the above-mentioned predetermined formula or rule is an example, and any formula or rule may be used for connection as long as it is possible to control the nanosecond wavelength selective switch. For example, if there is a free port, the formula or rule may take the free port into consideration.

[0065] As shown in Figure 13(a), it is preferable that m = 0 in the nanosecond wavelength selective switch. This makes it possible to configure a single-input, multiple-output, bidirectional nanosecond wavelength selective switch. Note that a multiple-input, single-output, bidirectional nanosecond wavelength selective switch in which the input port and output port of the nanosecond wavelength selective switch in Figure 13(a) are swapped, as shown in Figure 13(b), is also included in the nanosecond wavelength selective switch of the present invention.

[0066] As shown in Fig. 14, in a nanosecond wavelength selective switch, m ×2 n The optical switch unit preferably satisfies m ≥ 1. This makes it possible to configure a multiple-input, multiple-output, bidirectional nanosecond wavelength selective switch.

[0067] A specific example of a single-input, multiple-output, bidirectional nanosecond wavelength selective switch will be described. Fig. 15 is a schematic diagram showing an example of a nanosecond wavelength selective switch. In the example of Fig. 15, one input AWG, 256 1x256 optical switch units, and 256 output AWGs are logically arranged in series, and the output ports of the input AWGs and the input ports of the optical switch units, and the output ports of the optical switch units and the input ports of the output AWGs are connected according to a predetermined mathematical formula or rule. In addition, the input AWG has one input port and 256 output ports, and the output AWG has 256 input ports and one output port.

[0068] A specific example of a multiple-input, multiple-output, bidirectional nanosecond wavelength selective switch will be described. Fig. 16 is a schematic diagram showing an example of a nanosecond wavelength selective switch. In the example of Fig. 16, 16 input AWGs, 64 16x64 optical switch units, and 64 output AWGs are logically arranged in series, and the output ports of the input AWGs are connected to the input ports of the optical switch units, and the output ports of the optical switch units are connected to the input ports of the output AWGs according to a predetermined mathematical formula or rule. In addition, the input AWG has one input port and 64 output ports, and the output AWG has 64 input ports and one output port.

[0069] (Optical network configuration) An example of the configuration of an optical network using a nanosecond optical switch array or a nanosecond wavelength selective switch of the present invention will be described below. Figures 17 to 19 are schematic diagrams showing an example of an optical network according to an embodiment of the present invention. Figures 17 to 19 show an example of an optical network 300 using a nanosecond optical switch array 100 or a nanosecond wavelength selective switch 200 of the present invention.

[0070] FIG. 17 shows an example of a wavelength-tunable optical network 300 with one degree of freedom. The degree of freedom refers to the number of input / output ports connected from each node to the network. The multiple input / output ports of each node in the network 300 in FIG. 17 are connected one-to-one to some of the 256 input / output ports of the 1×256 nanosecond wavelength selective switch 210, and one input / output port of the 1×256 nanosecond wavelength selective switch 210 is connected to an input / output port of the 65,536×65,536 nanosecond optical switch array 140. In other words, the number of input / output ports connected from each node to the network is one. Each node can maintain communication for a certain period of time and connect to other nodes. During this period, the wavelength bandwidth can be changed. Interconnections with other nodes are achieved by controlling the nanosecond optical switch array, and can be reconfigured by controlling the nanosecond optical switch array. Note that in FIGS. 17 to 19, m and n represent the number of nodes. In FIG. 17, the maximum values ​​of m and n are 65,536. Also, in FIGS. 17 to 19, for convenience, the right-side node and the left-side node are treated as different nodes, but the same node may exist between the right-side node and the left-side node.

[0071] FIG. 18 shows an example of a three-degree-of-freedom, wavelength-independent optical network 300. The network 300 in FIG. 18 is equipped with three 65,536 × 65,536 nanosecond optical switch arrays 140. Each node has three input / output ports, and the jth input / output port of the ith node is connected to the ith input / output port of the jth nanosecond optical switch array. Each node can be simultaneously connected to up to three other nodes. Three input / output ports may be simultaneously connected to the same node. The wavelengths of the ports within a node are flexible and may be the same or different as long as there are no frequency conflicts. In FIG. 18, the maximum values ​​of m and n are 65,536.

[0072] FIG. 19 shows an example of a wavelength-tunable optical network 300 with d degrees of freedom. The input / output ports of each node in the network 300 in FIG. 19 are connected one-to-one to some of the 64 input / output ports of the 16×64 nanosecond wavelength selective switch 220, giving the network 16 input / output ports. Therefore, the maximum value of d is 16. The network 300 in FIG. 19 is equipped with d 65,536×65,536 nanosecond optical switch arrays 140. Each node has a maximum of d input / output ports, and the jth input / output port of the i-th node is connected to the i-th input / output port of the j-th nanosecond optical switch array. Each node can be simultaneously connected to a maximum of d other nodes. d input / output ports may be simultaneously connected to the same node. It is also possible to change the wavelength bandwidth during this process.

[0073] (Control Plane) 20 is a conceptual diagram of the control plane of the nanosecond optical switch array or nanosecond wavelength selective switch of the present invention. The nanosecond optical switch array or nanosecond wavelength selective switch of the present invention is controlled by, for example, a controller implemented in software on a server and a hardware agent on the board using synchronized digital signals (synchronized control signals).

[0074] In this way, the nanosecond optical switch array or nanosecond wavelength selective switch of the present invention can achieve high switching speeds even after scale expansion by using high-speed optical switches and synchronous control signals.

[0075] (Example) Using the first method, we fabricated a 4 × 4 nanosecond optical switch array, a 16 × 16 nanosecond optical switch array, a 256 × 256 nanosecond optical switch array, and a 65,536 × 65,536 nanosecond optical switch array. The 2 × 2 optical switch unit used a commercially available optical switch that operates on the order of nanoseconds. When these were used as optical switches, they all operated on the order of nanoseconds and could be used appropriately.

[0076] The insertion losses of the fabricated 4 × 4 nanosecond optical switch array, 16 × 16 nanosecond optical switch array, 256 × 256 nanosecond optical switch array, and 65,536 × 65,536 nanosecond optical switch array were approximately 0.7 dB, approximately 2.1 dB, approximately 6.3 dB, and approximately 18.9 dB, respectively. This confirms that the insertion loss of nanosecond optical switch arrays fabricated by the first method up to 65,536 × 65,536 is generally within the acceptable range.

[0077] Next, using the second method, we fabricated a 4 × 4 nanosecond optical switch array, a 16 × 16 nanosecond optical switch array, and a 65,536 × 65,536 nanosecond optical switch array. When these were used as optical switches, they all operated on the order of nanoseconds and could be used appropriately.

[0078] The insertion losses of the fabricated 4 × 4 nanosecond optical switch array, 16 × 16 nanosecond optical switch array, and 65,536 × 65,536 nanosecond optical switch array were approximately 0.7 dB, approximately 1.9 dB, and approximately 8.7 dB, respectively. This confirmed that the nanosecond optical switch array fabricated by the second method had lower loss than the nanosecond optical switch array fabricated by the first method. It was also confirmed that the insertion loss up to 65,536 × 65,536 was generally within the acceptable range.

[0079] In addition to the above, we fabricated a 1 × 4 nanosecond optical switch array, a 1 × 16 nanosecond optical switch array, a 1 × 256 nanosecond optical switch array, and a 16 × 64 nanosecond optical switch array. The 16 × 64 nanosecond optical switch array was fabricated using the 16 × 16 nanosecond optical switch array fabricated by the first method. When these were used as optical switches, they all operated on the nanosecond order and could be used appropriately. Furthermore, their insertion losses were approximately 0.4 dB, 0.8 dB, 1.6 dB, and 2.5 dB, respectively.

[0080] We also fabricated a 1 x 256 nanosecond wavelength selective switch and a 16 x 64 nanosecond wavelength selective switch. The 1 x 256 nanosecond optical switch array and the 16 x 64 nanosecond optical switch array described above were used, respectively. When these were used as wavelength selective switches, they operated on the order of nanoseconds and could be used appropriately. Furthermore, their insertion losses were approximately 3.6 dB and 3.6 dB, respectively.

[0081] As described above, the nanosecond optical switch array and nanosecond wavelength selective switch of the present invention achieve high switching speeds. Furthermore, low insertion loss and a simple construction method make it easy to scale up. For example, it is possible to interconnect 65,536 nodes. Furthermore, because the design is highly modular and does not require fixed connections, it can be used in a variety of optical networks, and it excels in adaptability to various topologies and wavelength resource accommodation efficiency. [Explanation of symbols]

[0082] 100 nanosecond optical switch array 110 4x4 nanosecond optical switch array 115 8x8 nanosecond optical switch array 120 16x16 nanosecond optical switch array 130 256×256 nanosecond optical switch array 140 65536×65536 nanosecond optical switch array 150 1x4 nanosecond optical switch arrays 160 1x16 nanosecond optical switch arrays 170 1×256 nanosecond optical switch array 180 16x64 nanosecond optical switch array 200 nanosecond wavelength selective switch 210 1x256 nanosecond wavelength selective switch 220 16x64 nanosecond wavelength selective switch 300 Optical Network System

Claims

1. A nanosecond optical switch array that switches communication paths of optical signals under the control of a controller, Multiple 2 ｉ ×2 ｉ an input-side optical switch unit (i≧1); ｊ ×2 ｊ a central optical switch unit (j≧2) and a plurality of 2 ｋ ×2 ｋ and an output-side optical switch unit (k≧1), which are logically arranged in series; an output port of the input-side optical switch unit and an input port of the central optical switch unit, and an output port of the central optical switch unit and an input port of the output-side optical switch unit are connected according to a predetermined mathematical formula or rule; the switching speeds of the input-side optical switch unit, the central optical switch unit, and the output-side optical switch unit are on the order of nanoseconds; A nanosecond optical switch array characterized in that the input side optical switch unit, the central optical switch unit, and the output side optical switch unit are synchronized and controlled by a digital signal from the controller.

2. i = j = k, and each ｉ 2. The nanosecond optical switch array according to claim 1, wherein the input-side optical switch units, the central optical switch unit, and the output-side optical switch unit are connected.

3. i = k = 1, and 2 ｊ the input side optical switch units, the two central optical switch units, and the two ｊ 2. The nanosecond optical switch array according to claim 1, wherein said output side optical switch units are connected.

4. Switching the communication path of optical signals 2 ｍ ×2 ｎ A nanosecond optical switch array, comprising: 1 of 2 ｍ ×2 ｍ an input-side optical switch unit (m≧2); ｍ Pieces of 1 x 2 ｎ－ｍ and an output-side optical switch unit (n-m≧1), which are logically arranged in series, 2. ｍ ×2 ｍ The output port of the input-side optical switch unit and the 1×2 ｎ－ｍ The input ports of the output-side optical switch units are connected one-to-one, 2. ｍ ×2 ｍ The input-side optical switch unit and the 1×2 ｎ－ｍ The switching speed of the output optical switch unit is on the order of nanoseconds and is synchronized and controlled by digital signals.

2. ｍ ×2 ｍ The input side optical switch unit is a nanosecond optical switch array according to claim 2 or 3. ｍ ×2 ｎ Nanosecond optical switch array.

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