JP2006243013A - Multi-port optical switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-port optical switch suitable for two-way optical communication. <P>SOLUTION: The multi-port optical switch has N ports (N: an integer of ≥3) and is so constituted that the ports can be connected to all other ports. Consequently, two-way communication between respective ports becomes possible. In an embodiment, a multi-port optical switch has N one-input, M-output optical switches (M: an integer of ≥N-1), which are interconnected through N-1 output ports. In another embodiment, a one-input, M-output optical switch comprises a plurality of two-input, two-output optical switches, and respective one-input, M-output optical switches are interconnected through cross-side output ports of the two-input, two-output optical switches. Consequently, an optical signal between ports passes through a cross port twice without fail to provide the one-input, M-output optical switch having a superior extinction ratio. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multi-port optical switch that changes an optical connection state between ports, and more particularly to a multi-port optical switch having a high extinction ratio suitable for bidirectional communication.

  With the rapid spread of optical communication systems, an optical switch that dynamically switches the optical path of an optical signal is desired in order to effectively use a limited optical fiber or configure an optical network with excellent flexibility. . In particular, the optical waveguide type optical switch is attracting attention because it can provide an optical switch having no mechanical movable part and excellent in reliability.

FIG. 1 shows a configuration of a conventional waveguide type double-gate 2-input 2-output optical switch for switching optical signals. The waveguide-type double-gate 2-input 2-output optical switch shown in FIG. 1 includes a first waveguide-type 2-input 2-output optical switch 106a and a second waveguide-type 2-input 2-output optical switch on a substrate 100. 106b, a third waveguide type 2-input 2-output optical switch 112a,
And a fourth waveguide type two-input two-output optical switch 112b, and the first and second waveguide type two-input two-output optical switches are connected to the third and fourth waveguide type two-inputs via the optical path 107. Connected to a two-output optical switch.

  The first waveguide type 2-input 2-output optical switch 106a includes optical couplers 102b and 105a having a coupling rate of 50% and optical waveguide arms 103a and 104a, and the optical coupler 102a is connected to the input optical waveguide 101a. The optical coupler 105 a is connected to the optical path 106. The second waveguide type 2-input 2-output optical switch 106b includes optical couplers 102b and 105b having a coupling rate of 50% and optical waveguide arms 103b and 104b. The optical coupler 102b is connected to the input optical waveguide 101b. The optical coupler 105 b is connected to the optical path 106.

  The third waveguide type 2-input 2-output optical switch 112a includes optical couplers 108a and 111a having a coupling ratio of 50% and optical waveguide arms 109a and 110a. The optical coupler 111a serves as the output optical waveguide 113a. The optical coupler 108a is connected to the optical path. The fourth waveguide type 2-input 2-output optical switch 112b includes optical couplers 108b and 111b having a coupling rate of 50% and optical waveguide arms 109b and 110b, and the optical coupler 111b is connected to the input optical waveguide 113b. The optical coupler 108b is connected to the optical path.

  Thin film heaters are formed on the optical waveguide arms 104a, 104b, 110a, and 110b so that the phase of light can be changed through the thermo-optic effect. Therefore, by applying power to the thin film heater, the optical connection state between the input optical waveguides 101a and 101b and the output optical waveguides 113a and 113b can be changed.

  In the waveguide type double-gate two-input two-output optical switch of FIG. 1, the optical signal of each of the waveguide-type two-input two-output optical switches 106a, 106b, 112a, 112b is in any optical connection state. Each waveguide type two-input two-output optical switch is configured to pass once. Since the extinction ratio of the cross port of the waveguide type 2-input 2-output optical switch is not deteriorated even if the optical coupler deviates from 50%, this configuration causes the optical couplers 102a, 105a due to factors such as manufacturing errors. , 102b, 105b, 108a, 111a, 108b, and 111b can realize a waveguide type double-gate 2-input 2-output optical switch having a good extinction ratio even when the coupling ratio deviates from 50%.

  However, the conventional optical switch has a configuration having an input optical port and an output optical port, and is not suitable for applications in which input / output such as bidirectional optical communication is performed on the same port. In addition, since the conventional optical switch is configured to pass through the cross port only once, the extinction ratio has a limit.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a multi-port optical switch having a high extinction ratio suitable for bidirectional optical communication.

  In order to achieve the above object, the present invention provides a multi-port optical switch capable of changing an optical connection state between ports, wherein N ports (N is And an M output optical switch (M is an integer equal to or more than N−1), each of which is connected to N−1 output ports. And an M output optical switch connected to each other.

  The invention according to claim 2 is the multi-port optical switch according to claim 1, wherein at least one of the M output optical switches further includes an output port connected to a reflection mirror. To do.

  According to a third aspect of the present invention, in the multiport optical switch according to the first or second aspect, the M output optical switch includes a plurality of two-input two-output optical switches, The output port is a cross-side port of the 2-input 2-output optical switch.

  The invention according to claim 4 is the multiport optical switch according to any one of claims 1 to 3, wherein the multiport optical switch is a waveguide type formed on a single substrate. It is characterized by being.

The invention according to claim 5 is the multi-port optical switch according to claim 4,
Some of the N ports are arranged on different sides of the substrate.

  The invention according to claim 6 is the multi-port optical switch according to claim 4 or 5, wherein the substrate is a silicon substrate and the waveguide is a silica-based optical waveguide. .

  The invention according to claim 7 is the multi-port optical switch according to any one of claims 4 to 6, wherein the N-1 output ports are connected to each other by an optical fiber sheet. It is characterized by that.

  The invention according to claim 8 is a multi-port optical switch capable of changing an optical connection state between multi-ports, wherein the plurality of multi-port optical switches according to claim 1 are connected to the port. It is characterized by being connected to each other via a part of.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiment of the present invention, elements having the same function are denoted by the same reference numerals, and redundant description thereof is omitted. In the following embodiments, the optical circuit is described as a silica-based optical waveguide formed on a silicon substrate. This is because this combination can provide an optical circuit with excellent reliability. However, the present invention is not limited to this, and other substrates such as quartz and other waveguide materials such as dielectrics and semiconductors may be used.

(First embodiment)
FIG. 2 shows a configuration of a waveguide type multiport optical switch according to the second embodiment of the present invention. The waveguide-type multiport optical switch 31 includes N (N = 6 in FIG. 2) input / output optical ports 11 on the substrate 10 and N 1-input M-output waveguide optical switches 12 (M in FIG. 2). = N-1 = 5) and N (N-1) / 2 (15 in FIG. 2) optical paths 13 for connection. Here, in the waveguide-type multiport optical switch according to the first embodiment of the present invention shown in FIG. 2, N = 6, but the present invention is not limited to this example, and N may be 3. Eight is okay.

  In the waveguide type multi-port optical switch 31 shown in FIG. 2, the input port of each one-input five-output waveguide type optical switch 12 is optically connected to the input / output port 11, and the output port is a connection light. The path 13 is optically connected to the output port of another 1-input M-output waveguide type optical switch. The connection optical path 13 in FIG. 2 is configured so that the number of intersections is reduced in order to prevent an increase in loss due to waveguide intersections. Of course, the waveguide intersections other than those shown in FIG. Note that it may be used.

  2, the optical connection state between the input / output ports 11 can be changed by switching the connection state of the one-input five-output waveguide optical switch 12 respectively. . In FIG. 2, the first input / output port 11a and the fifth input / output port 11e are optically connected, and the second input / output port 11b and the third input / output port 11c are optically connected. In this example, the fourth input / output port 11d and the sixth input / output port 11f are optically connected. Here, this combination of optical connections is, of course, an example, and other optical connection states are possible. In particular, it should be noted that a many-to-one or one-to-many connection in which both the input / output port 11a and the input / output port 11b are optically connected to the input / output port 11c is possible.

  Next, a configuration example of the 1-input M-output waveguide type optical switch 12 used in the waveguide type multiport optical switch 31 shown in FIG. 2 will be described. FIG. 3 shows the configuration. This 1-input M-output waveguide type optical switch 12 (M = 5 in the case of FIG. 2) includes M 2-input 2-output waveguide type optical switches 25 connected in series, and the cross-side port outputs It is connected to the optical waveguide 26 for use.

  The 2-input 2-output waveguide type optical switch 25 is realized by a Mach-Zehnder configuration including optical couplers 21 and 24 and optical waveguide arms 22 and 23. Further, as shown in the drawing, a thin film heater is formed on the optical waveguide arm 23 so that the phase of light can be changed through the thermo-optic effect.

  In the 2-input 2-output waveguide optical switch 12, the through-side output optical waveguide of the front-stage 2-input 2-output waveguide-type optical switch 25 is used for one input of the rear-stage 2-input 2-output waveguide-type optical switch 25. It is connected to the waveguide and is configured to be the cross-side output optical waveguide 26 of the preceding two-input two-output waveguide optical switch 25. Therefore, an optical signal always passes through the cross port when it is output, and a 1-input M-output optical switch having an excellent extinction ratio can be provided. Further, by using the 1-input M-output waveguide type optical switch having such a configuration, the waveguide type multi-port optical switch of FIG. 2 is configured, so that an optical signal propagating between the ports always passes through the cross port twice. Since it becomes the structure which passes, a high extinction ratio is realizable.

  Here, in the first embodiment of the present invention, the optical couplers 21 and 24 are directional couplers. This is because this configuration can provide a low-loss waveguide multiport optical switch. However, the present invention is not limited to this example, and the optical couplers 21 and 24 may of course be multimode interference optical couplers or X-branches.

  In the waveguide multiport optical switch of this embodiment, the 1-input M-output waveguide optical switch is realized by the cascade-connected 2-input 2-output waveguide optical switch 25 shown in FIG. This is because this combination can provide a waveguide type multi-port optical switch having an excellent extinction ratio. However, the waveguide type multi-port optical switch of the present invention is not limited to this example. For example, a 2-input 2-output waveguide type optical switch configured in a tree shape or a so-called extended Mach-Zehnder interferometer 1 You may use the structure which consists of an input M output optical coupler, M waveguide arms, and an M input M output optical coupler.

  Next, a configuration example in which the waveguide type multiport optical switches 31 shown in FIG. 2 are connected to each other will be described. FIG. 4 shows the configuration. In this configuration example, the input / output port 11f of the first waveguide type multiport optical switch 31a is connected to the input / output port 11g of the second waveguide type multiport optical switch 31b. The input / output ports 11k and 11l of the multiport optical switch 31b are connected to the input / output ports 11m and 11n of the third waveguide type multiport optical switch 31c, respectively.

  Therefore, as a whole, it functions as a multi-port optical switch having 12 input / output ports. In the example of FIG. 4, the input / output port 11a is 11c, the input / output port 11b is 11d, and the input / output port 11e is 11f through 11f, 11g, 11k, and 11n, 11j through input / output port 11h, 11j through input / output port 11i, 11q through 11m, and 11r through input / output port 11p are optically connected to 11r, respectively. .

  Combining a plurality of waveguide type multi-port optical switches in this way has the advantage that the number of ports of the waveguide type multi-port optical switch can be easily increased. However, it should be noted that an optical connection state between arbitrary input / output ports cannot be realized by a combination of a plurality of waveguide type multi-port optical switches.

  The above-mentioned optical connection state is an example, and the waveguide type multi-port optical switch may be connected so as to form an annular shape, or another connection configuration may be used.

(Second Embodiment)
FIG. 5 shows a configuration example of a waveguide type multi-port optical switch according to the second embodiment of the present invention. In the waveguide type multi-port optical switch 51, N (N = 6 in FIG. 5) input / output ports are arranged at the opposite ends of the N-type waveguide multi-port optical switch.

  Input / output ports 11 arranged at both ends are connected to input ports of a 1-input M-output waveguide type optical switch 12 (M = N−1 = 5 in FIG. 5), and each 1-input M-output waveguide type. The output port of the optical switch 12 is connected to the output port of another one-input M-output waveguide type optical switch 12 by N (N−1) / 2 (15 in FIG. 5) connection optical paths 13. ing.

  Even with such a configuration, the waveguide type multi-port optical switch of the present invention can be provided. In addition, such a configuration has an advantage that the area occupied by the waveguide type multi-port optical switch can be reduced as compared with the configuration of FIG.

  The arrangement of the connection optical path of the waveguide type multi-port optical switch according to the second embodiment of the present invention shown in FIG. 5 is an example, and the output port of each input / output waveguide type optical switch 12 is an example. However, it should be noted that any connection method may be used as long as it is connected to the output port of another one-input M-output waveguide type optical switch 12.

(Third embodiment)
FIG. 6 shows a configuration example of a waveguide type multi-port optical switch according to the third embodiment of the present invention. The waveguide type multi-port optical switch 71 includes N (N = 6 in FIG. 6) 1-input M-output waveguide optical switches 12 (M = N−1 = 5 in FIG. 6) formed on the substrate 10. The connection optical path 13 is formed on the fiber sheet 40. The optical fiber sheet 40 and the substrate 10 are fixed with an adhesive.

  Even with such a configuration, the waveguide type multi-port optical switch of the present invention can be provided. Compared with the configuration of FIG. 2, the feature of this configuration is that waveguide crossings can be avoided, so that an increase in loss due to waveguide crossings and deterioration of crosstalk can be suppressed.

  In the waveguide multiport optical switch according to the third embodiment of the present invention, the input / output port 11 and the 1-input M-output waveguide optical switch 12 are all formed on the same substrate. May be separate and separate substrates. It is an advantage to use the optical fiber sheet 40 that it can be configured by an individual substrate in this way.

  Furthermore, in the waveguide type multi-port optical switch according to the third embodiment of the present invention, the connection optical path 13 is realized on the optical fiber sheet 40. This is compact, inexpensive and easy to handle. This is because an excellent waveguide type multi-port optical switch can be provided. However, the connection optical path 13 may of course be realized by an optical fiber or the like.

(Fourth embodiment)
FIG. 7 shows a configuration example of a waveguide type multi-port optical switch according to the fourth embodiment of the present invention. The waveguide type multi-port optical switch 91 includes N input / output ports 11 (N = 4 in FIG. 7) on the substrate 10 and N 1-input M output waveguide type optical switches 12 (M = in FIG. 7). 4), N (N-1) / 2 (six in FIG. 7) connection optical paths 13, and a reflection mirror 66 optically connected via an output waveguide 65. .

  The reflection mirror 66 is realized by depositing gold on the waveguide end. This is because this configuration can provide a reflection mirror that is easy to manufacture. However, the present invention is not limited to this example, and a metal material such as gold or aluminum may be deposited by etching the end face of the waveguide, or a reflection mirror by another method such as a waveguide loop mirror. May be provided.

  Here, the 1-input M-output waveguide type optical switch 12 (M = 4 in FIG. 7) is composed of (M−1) (3 in FIG. 7) 2-input 2-output waveguide type optical switches 25. The cross-side port is connected to the output optical waveguide 13, and the through-side port is connected to the output optical waveguide 65. The 2-input 2-output waveguide type optical switch 25 is composed of optical couplers 61 and 64 and optical waveguide arms 62 and 63. Thin film heaters are formed on the optical waveguide arms 62 and 63, respectively, so that phase modulation can be performed via the thermo-optic effect.

  In the waveguide type multiport optical switch shown in FIG. 7, for example, an optical signal input to the input / output port 11a can be connected to any one of the input / output ports 11b, 11c, and 11d, or the input / output port 11a. It can also be returned to. Therefore, failure diagnosis of the waveguide type multi-port optical switch can be performed, and a waveguide type multi-port optical switch excellent in maintainability can be provided. In this configuration, the connection from one port to any other port is configured such that the optical signal always passes through the cross port twice. Thereby, the 1-input M output optical switch excellent in the extinction ratio can be provided.

  Actually, a waveguide type multi-port optical switch shown in FIG. 7 was fabricated, and the extinction ratio characteristic was evaluated. The waveguide type multi-port optical switch shown in FIG. 7 was produced by a quartz optical waveguide formed on a silicon substrate. The relative refractive index difference between the core and the clad of the silica-based optical waveguide was 1.5%. By using such a relative refractive index difference, the minimum bending radius of the waveguide can be set to 2 mm, and a small-sized waveguide type multiport optical switch is provided while maintaining consistency with the optical fiber. Because it can. However, the present invention is not limited to this example, and the relative refractive index difference may be 0.4% or 3%.

  FIG. 8 shows the extinction ratio characteristics of the fabricated waveguide type multiport optical switch. In addition, the connection port shown in FIG. 8 has shown the path | route of four input / output ports. As shown in FIG. 8, the waveguide type multi-port optical switch of FIG. 7 can realize a high extinction ratio of −45 dB or less. Thus, a high extinction ratio can be realized by configuring the optical signal to pass through the cross port twice.

  Although the present invention has been specifically described above based on some embodiments, the embodiments described herein are merely illustrative in view of many possible embodiments to which the principles of the present invention can be applied. However, it does not limit the scope of the present invention. Therefore, the configuration and details of the embodiment exemplified here can be changed without departing from the spirit of the present invention. Further, the components for explanation may be changed, supplemented, or changed in order without departing from the spirit of the present invention.

It is a figure which shows the structure of the conventional waveguide type double gate 2 input 2 output optical switch. It is a figure which shows the structure of the waveguide type multiport optical switch which concerns on one Embodiment of this invention. It is a figure which shows the structure of 1 input M output waveguide type | mold optical switch which can be used for the waveguide type | mold multiport optical switch which concerns on one Embodiment of this invention. It is a figure which shows the structure which connected two or more waveguide type | mold multiport optical switches which concern on one Embodiment of this invention. It is a figure which shows the structure of the waveguide type multiport optical switch which concerns on one Embodiment of this invention. It is a figure which shows the structure of the waveguide type multiport optical switch which concerns on one Embodiment of this invention. It is a figure which shows the structure of the waveguide type multiport optical switch which concerns on one Embodiment of this invention. A waveguide-type multiport optical switch according to an embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Board | substrate 11 Input / output optical port 12 1 input M output optical switch 13 Optical path for connection 21 Optical coupler 22 Optical waveguide arm 23 Optical waveguide arm (with thin film heater)
24 optical coupler 25 2-input 2-output optical switch 26 optical waveguide for output 31 multiport optical switch 40 optical fiber sheet 51 multiport optical switch 61 optical coupler 62 optical waveguide arm (with thin film heater)
63 Optical waveguide arm (with thin film heater)
64 Optical coupler 65 Output waveguide 66 Reflecting mirror 71 Multiport optical switch 91 Multiport optical switch 100 Substrate 101 Optical waveguide for input 102 Optical coupler 103 Optical waveguide arm 104 Optical waveguide arm (with thin film heater)
105 optical coupler 106 2-input 2-output optical switch 107 optical path 108 optical coupler 109 optical waveguide arm 110 optical waveguide arm (with thin film heater)
111 optical coupler 112 2-input 2-output optical switch 113 optical waveguide for output

Claims (8)

A multi-port optical switch capable of changing the optical connection state between ports,
N ports (N is an integer greater than or equal to 3),
An M output optical switch (M is an integer equal to or more than N−1) in which an input port is connected to each of the N ports, each of which is connected to each other via N−1 output ports. A multi-port optical switch characterized by comprising an output optical switch. The multi-port optical switch according to claim 1.
The multi-port optical switch, wherein at least one of the M output optical switches further includes an output port connected to a reflection mirror. The multi-port optical switch according to claim 1 or 2,
The M output optical switch is composed of a plurality of 2-input 2-output optical switches,
The N-1 output ports are cross-side ports of the 2-input 2-output optical switch. The multi-port optical switch according to any one of claims 1 to 3,
The multi-port optical switch is a waveguide type formed on a single substrate. The multi-port optical switch according to claim 4,
The multi-port optical switch according to claim 1, wherein some of the N ports are arranged on different sides of the substrate. The multi-port optical switch according to claim 4 or 5,
The multiport optical switch, wherein the substrate is a silicon substrate, and the waveguide is a silica-based optical waveguide. The multi-port optical switch according to any one of claims 4 to 6,
The multi-port optical switch, wherein the N-1 output ports are connected to each other by an optical fiber sheet. A multi-port optical switch capable of changing an optical connection state between multi-ports,
A multi-port optical switch comprising a plurality of the multi-port optical switches according to claim 1 connected to each other through a part of the ports.

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