JP3444548B2 - Light switch - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch used for optical signal exchange processing. In particular, it relates to an optical switch used for exchanging optical signals of different wavelengths transmitted by a wavelength division multiplexing communication system.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show the structure of an optical matrix switch. In addition, this configuration is Japanese Patent Application No. 5-23821.
It is disclosed in the specification of No. 4.

In the configuration shown in FIG. 5, the number of input ports M is 5,
The number of output ports N is four. This input port 11
˜15 and output ports 21 to 24, the 1-input 2-output optical switch 31-1 is located at the intersection of the M × N matrix.
˜35-4 are arranged, and 5 input optical signal combiners 41 to 44 are arranged at each output port. The optical signals input from the input ports 11 to 15 are four 1-input 2-output optical switches 31-1 to 31-4 and 32-
1-32-4, 33-1 to 33-4, 34-1 to 34-
4, 35-1 to 35-4 selected and corresponding 5
It is sent to the input optical signal combiners 41 to 44. In each of the five-input optical signal combiners 41 to 44, five 1s arranged in the column direction are arranged.
Input 2 output optical switches 31-1 to 35-1, 31-2 to
The outputs of 35-2, 31-3 to 35-3, 31-4 to 35-4 are merged, and the corresponding output ports 21 to 24 are connected.
Send to.

With such a configuration, it is possible to distribute an optical signal of an arbitrary wavelength input to each input port to each output port in any combination. That is, it is also possible to wavelength-multiplex optical signals input from different input ports to the same output port and send them out.

The configuration shown in FIG. 6 has a wavelength multiplexing signal input port 51 and an optical signal demultiplexer 6 in the input stage of the configuration shown in FIG.
1 is provided. The wavelength-multiplexed signal input port 51 is input with wavelength-multiplexed optical signals of wavelengths λ _{1 to} λ ₅ , and the optical signal demultiplexer 61 demultiplexes the wavelength-multiplexed signal for each wavelength to input ports 11 to 11. Enter in 15. Furthermore, in this configuration example, 5-input optical signal multiplexers 71 to 74 are used instead of the 5-input optical signal multiplexers 41 to 44. With such a configuration, the wavelength-multiplexed optical signals of wavelengths λ _{1 to} λ ₅ input to the wavelength-multiplexed signal input port 51 can be distributed to each of the four output ports in any combination.

[0006]

In the M-input / N-output optical matrix switch as shown in FIGS. 5 and 6, the number of 1-input 2-output optical switches passing through differs depending on the optical signal distributed to each output port. . If the insertion loss of one 1-input 2-output optical switch is L ₁ (dB) and the insertion loss of the optical signal multiplexer and the optical signal multiplexer is L ₂ (dB), the minimum insertion loss is 1 It becomes L ₁ + L ₂ (dB) when passing through the input 2 output optical switch, and the maximum insertion loss becomes N × L ₁ + L ₂ (dB) when passing through N N 1 input 2 output optical switches. That is, a maximum (N-1) L ₁ (dB) insertion loss difference occurs depending on the optical signal path (output port).

However, it is generally desirable that the insertion losses due to the paths are equal. Therefore, in the case of the configurations shown in FIGS. 5 and 6, a dummy switch or the like is added to the output ports 21, 22, and 23, generally (N-1) or less 1-input 2-output optical switch. It was necessary to make the insertion loss uniform in all the paths so that the maximum insertion loss was N × L ₁ + L ₂ (dB).

According to the present invention, optical signals of different wavelengths inputted to the respective input ports can be distributed to the respective output ports in any combination, and further, the loss depending on the switching path of the optical signal can be made uniform and small. It is an object of the present invention to provide an optical switch capable of

[0009]

The optical switch of the present invention comprises:
M 1-input N-output optical switches respectively connected to the M input ports and transmitting the optical signals input from the input ports to any of the N output lines, and M 1-input N-output optical switches Connected between each output line and N output ports, and merges the outputs of the M 1-input N-output optical switches and sends them to the corresponding output ports. And an optical switch having M inputs and N outputs is configured as a whole (Claim 1).

In place of the N M-input optical signal combiners, N M-input optical signal combiners for multiplexing the outputs of the M 1-input N-output optical switches and sending them to the corresponding output ports. A wave instrument is provided (Claim 2).

In the 1-input N-output optical switch, the 1-input 2-output optical switch is connected in multiple stages in a two-branch configuration, and the optical signal input from the input port corresponds to the output port of the N output lines. The configuration is such that the output is sent to one output line (claim 3).

Further, an optical gate switch is inserted into the N output lines of the 1-input N-output optical switch, the optical gate switch of the output line to which the optical signal is transmitted is turned on, and the optical gate switches of the other output lines are turned on. Is turned off to prevent passage of an optical signal (crosstalk component) (claim 4).

The optical gate switch is in an on state when power is applied and is in an off state when power is not applied (claim 5). In addition, a 1-input M-output optical signal demultiplexer for inputting wavelength-multiplexed optical signals, demultiplexing for each wavelength, and inputting to each of the M input ports is provided in front of the M input ports ( Claim 6).

[0014]

In the optical switch of the present invention, the optical signal input from the input port is sent from the 1-input N-output optical switch to the M-input optical signal combiner corresponding to the output port. The M input optical signal combiner combines the optical signals from the other input ports and outputs the combined optical signals to the output port. As a result, optical signals of different wavelengths input to the input ports can be distributed to the output ports in any combination.

Here, the loss in a 1-input N-output optical switch constructed by connecting 1-input 2-output optical switches in a two-branch configuration in multiple stages is the insertion loss of one 1-input 2-output optical switch being L ₁ (DB), if N is a power of 2, log ₂ N × L ₁ . Therefore, the loss in the M-input / N-output optical switch according to the present invention is equal to the insertion loss of the M-input optical signal multiplexer.
_{If it is 2} (dB), it becomes log ₂ N × L ₁ + L ₂ (dB), which can be greatly reduced as compared with the conventional N × L ₁ + L ₂ (dB). Moreover, it is possible to equalize the loss of the optical signal for each switching path.

Further, by using the M input optical signal multiplexer instead of the M input optical signal multiplexer, the insertion loss L ₂ can be greatly reduced. Therefore, the loss of the entire optical switch can be reduced.

Further, by inserting an optical gate switch into the output line of the 1-input N-output optical switch, turning on the optical gate switch corresponding to the path of the optical signal and turning off the other,
It is possible to prevent the crosstalk from flowing out in the input N output optical switch.

Further, one of the N output lines of the optical gate switch is turned on and (N-1) lines are turned off. Therefore, by turning on the optical gate switch when power is applied and turning it off when power is not applied, it is possible to suppress the overall power consumption to a low level as compared with the case where it is reversed.

Further, by providing a 1-input M-output optical signal demultiplexer in the preceding stage of the M input ports (1-input N-output optical switch), the wavelength-multiplexed optical signal is demultiplexed, and each wavelength is demultiplexed. It can be switched to any output port.

[0020]

FIG. 1 shows a first embodiment of the present invention (claims 1, 3).
(Corresponding to) is shown. Here, the number of input ports M
5 and the number N of output ports is 4, but both the number of input ports and the number of output ports can be configured as desired.

In the figure, five input ports 11-15
1-input 4-output optical switches 81 to 8 provided corresponding to
5 are 1-input 2-output optical switches 31-1 to 31 respectively.
-3, 32-1 to 32-3, 33-1 to 33-3, 34
This is a configuration in which -1 to 34-3 and 35-1 to 35-3 are connected in multiple stages in a two-branch configuration. 1-input 4-output optical switch 81
The four output lines of 5 correspond to the output ports 21 to 24.
It is connected to each of the input optical signal combiners 41 to 44. Similarly, each of the four output lines of the 1-input 4-output optical switches 82-85 is connected to the 5-input optical signal combiners 41-44 corresponding to the output ports 21-24.

1-input 4-output optical switches 81 to 81 of this embodiment.
The 1-input 2-output optical switches 31 to 35, which constitute 85,
Mach-Zehnder interferometer type switch with wavelength demultiplexing function (Masao Kawauchi, "Planar lightwave circuit technology", NTT R & D,
vol.40, No.2, pp.199-204 (1990)) 1)
Used with 2 inputs and 2 outputs. Alternatively, if it can operate in the wavelength band to be used, an optical switch using a semiconductor, a waveguide switch, an optical gate switch using an element capable of controlling the passage or blocking of light such as a liquid crystal or an acousto-optic element. Can be used.

The five-input optical signal multiplexers 41 to 44 are constructed so as to couple an optical signal to one output port, for example, by using one of the outputs of a multistage coupler or a star coupler fused with an optical fiber. In addition, 5 input optical signal combiners 41-
At 44, since the input optical signals are wavelength-multiplexed, it is a principle to input the optical signals of different wavelengths to the respective input ports of the 5-input optical signal combiner. However, if the optical signals of the input ports 11 to 15 are not output to the same output port, the optical signals of the same wavelength may be input from different input ports.

Here, as a specific switching example,
The optical signal input from the input port 11 is output to the output port 23.
The case of outputting to will be described. 1-input 2-output of 1-input 4-output optical switch 81 corresponding to input port 11
The output of the output optical switch 31-1 is set to the b side, and the 1st input 2 output optical switch 31 of the second stage corresponding to this output b side
-3 output is set to a side. As a result, the optical signal input from the input port 11 is sent to the 5-input optical signal combiner 43 via the 1-input 2-output optical switches 31-1 and 31-3. The 5-input optical signal combiner 43 combines the optical signals from the other input ports and outputs the combined optical signals to the output port 23.
There is only one route.

FIG. 2 shows a second embodiment of the present invention (claims 2 and 3).
(Corresponding to 3 and 6). The present embodiment is a configuration example for distributing wavelength-multiplexed optical signals of wavelengths λ _{1 to} λ ₅ to each of the four output ports in an arbitrary combination. Both the number of wavelength division multiplexing and the number of output ports can correspond to arbitrary numbers.

In the figure, wavelength multiplexed signal input port 51
The wavelength-multiplexed optical signals of wavelengths λ _{1 to} λ ₅ are input to the input terminal. This WDM optical signal has 1 input 5 output optical signal demultiplexer 6
1 is demultiplexed for each wavelength and is input to the five input ports 11 to 15 of the 5-input 4-output optical switch according to the present invention. 5 input ports 11-15, 4 output ports 2
1 to 24 and 1-input 4-output optical switches 81-85 are the same as in the first embodiment, but 5-input optical signal combiner 4 is used.
The 5-input optical signal multiplexers 71 to 74 are used instead of 1 to 44. The optical signal multiplexer has a configuration in which an optical signal is coupled to one output port by utilizing the difference in reflection angle for each wavelength due to a grating, for example, and the insertion loss can be made smaller than that of the optical signal multiplexer. . The optical signal combiner can also be used in this embodiment.

In the configuration of this embodiment, each input port 11 to 11 is
Since the optical signals of different wavelengths are input to 15, the requirements of the configuration of the first embodiment are inevitably achieved. The function as an optical switch with 5 inputs and 4 outputs is the same as that of the first embodiment, and wavelength-multiplexed wavelengths λ _{1 to} λ _{5 are used.}
Each optical signal can be distributed to each output port in any combination. That is, each optical signal can be wavelength-multiplexed and sent to the same output port in any combination.

FIG. 3 shows a third embodiment of the present invention (claim 4).
(Corresponding to 5). The present embodiment is based on the configuration of the first embodiment, and each 1-input 4-output optical switch 81-8.
5 to the output line of the optical gate switches 91-1 to 91-4,
92-1 to 92-4, 93-1 to 93-4, 94-1 to
94-4, 95-1 to 95-4 are inserted.
Further, the four optical gate switches for one one-input, four-output optical switch are controlled so that only one optical gate switch allows light to pass and the other optical gate switches block light. As a result, the 1-input 4-output optical switch 81-
In 85, 1-input 2-output optical switches 31-1 to 35
It is possible to reduce crosstalk to the non-switching side due to -3 switching.

The optical gate switches 91-1 to 95-4 are
An element such as a liquid crystal or an acousto-optic element that can control the passage or blocking of light is used. Alternatively, the output of one of the Mach-Zedda interferometer-type switches can be used. Further, as long as it can operate in the wavelength band used, one output of an optical switch using a semiconductor or a waveguide switch can be used. However, the optical gate switch is turned on when light for switching control is applied and allows light to pass therethrough, and is turned off when power for switching control is not applied to block light. By using such an element, an M-input / N-output optical switch with low power consumption and small crosstalk can be configured.

Here, as a specific switching example,
The optical signal input from the input port 11 is output to the output port 23.
The case of outputting to will be described. 1-input 2-output of 1-input 4-output optical switch 81 corresponding to input port 11
The output of the output optical switch 31-1 is set to the b side, and the 1st input 2 output optical switch 31 of the second stage corresponding to this output b side
-3 output is set to a side. Further, of the optical gate switches 91-1 to 91-4, the optical gate switch 91-3
Is turned on and other optical gate switches are turned off. As a result, the optical signal input from the input port 11 is sent to the 5-input optical signal combiner 43 via the 1-input 2-output optical switches 31-1, 31-3 and the optical gate switch 91-3. Also, the 1-input 2-output optical switch 31-
The crosstalk components at 1, 31-3 are blocked by the optical gate switches 91-1, 91-2, 91-4. 5
The input optical signal combiner 43 combines the optical signals from the other input ports and outputs the combined optical signals to the output port 23. There is only one route.

FIG. 4 shows a fourth embodiment of the present invention (claim 4).
(Corresponding to 5 and 6). The present embodiment is a configuration example for distributing the wavelength-multiplexed optical signals of wavelengths λ _{1 to} λ ₅ to each of the four output ports in an arbitrary combination in the configuration of the third embodiment. Both the number of wavelength division multiplexing and the number of output ports can correspond to arbitrary numbers.

In the figure, wavelength multiplexed signal input port 51
The wavelength-multiplexed optical signals of wavelengths λ _{1 to} λ ₅ are input to the input terminal. This WDM optical signal has 1 input 5 output optical signal demultiplexer 6
1 is demultiplexed for each wavelength and is input to the five input ports 11 to 15 of the 5-input 4-output optical switch according to the present invention. 5 input ports 11-15, 4 output ports 2
1 to 24, 1-input 4-output optical switches 81-85, and optical gate switches 91-1 to 95-4 have the same coupling relationship as in the third embodiment, but instead of 5-input optical signal combiners 41 to 44. The 5-input optical signal multiplexers 71 to 74 are used. The optical signal multiplexer has a configuration in which an optical signal is coupled to one output port by utilizing a difference in reflection angle for each wavelength due to a grating, for example. It is possible to use an optical signal combiner.

In the configuration of this embodiment, the function as a 5-input 4-output optical switch is the same as that of the third embodiment, and the wavelength-multiplexed optical signals of wavelengths λ _{1 to} λ ₅ are arbitrarily output to the respective output ports. Can be sorted by the combination of. That is,
It is possible to wavelength-multiplex each optical signal to the same output port in an arbitrary combination and send it out.

[0034]

As described above, the M input N of the present invention is
The output optical switch can distribute optical signals of different wavelengths input from the respective input ports to the respective output ports in any combination including wavelength multiplexing. Moreover, an M-input / N-output optical switch is configured by the 1-input / N-output optical switch in which the 1-input / 2-output optical switch is connected in multiple stages in a two-branch configuration, and the M-input optical signal combiner or M-input optical signal multiplexer. By doing so, the number of 1-input 2-output optical switches on the optical signal switching path can be reduced as compared with the matrix type. As a result, the loss of the optical signal depending on the switching path can be made uniform and small.

By using a one-input / two-output optical switch, it is possible to reduce the accumulation of crosstalk. Further, by providing an optical gate switch capable of controlling passage / blocking of an optical signal in each output line of the 1-input 2-output optical switch, an optical switch with even smaller crosstalk can be realized. As a result, the SN ratio of the optical signal is improved, and it is possible to handle high-speed optical signals.

Further, by turning on the optical gate switch when power is applied and turning it off when power is not applied, the overall power consumption can be suppressed low. Further, by providing the optical signal demultiplexer in the preceding stage of the input port, it is possible to realize a 1-input N-output optical switch that switches the wavelength-multiplexed optical signal to an arbitrary output port for each wavelength.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a second embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of a third embodiment of the present invention.

FIG. 4 is a block diagram showing the configuration of a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an optical matrix switch.

FIG. 6 is a block diagram showing a configuration of an optical matrix switch.

[Explanation of symbols]

11-14 Input port 21-24 output ports 31-1 to 35-4 1-input 2-output optical switch 41-44 5 input optical signal combiner 51 WDM signal input port 61 Optical signal demultiplexer 71-74 5 input optical signal multiplexer 81-85 1-input 4-output optical switch 91-1 to 91-4 Optical gate switch

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masayuki Okuno 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (56) References JP-A-62-20493 (JP, A) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) H04Q 3/52 H04B 10/02 H04J 14/00 H04J 14/02

Claims (6)

(57) [Claims] 1. An optical switch having a plurality of M input ports and a plurality of N output ports, which outputs an optical signal input from an arbitrary input port to an arbitrary output port, wherein the input is made from each of the input ports. M 1-input N-output optical switches for sending the generated optical signals to any of the N output lines, and N-pieces for merging the outputs of the 1-input N-output optical switches and sending them to each output port. And an M input optical signal multiplexer. 2. The optical switch according to claim 1, wherein instead of N M-input optical signal combiners, N switches for multiplexing outputs of 1-input N-output optical switches and sending them to respective output ports. 2. An optical switch comprising the M-input optical signal multiplexer of. 3. The optical switch according to claim 1 or 2, wherein the 1-input N-output optical switch is configured by connecting 1-input 2-output optical switches in a two-branch configuration in multiple stages and inputting light from an input port. An optical switch having a configuration for sending a signal to one output line corresponding to an output port among N output lines. 4. The optical switch according to claim 3, wherein an optical gate switch is inserted into the N output lines of the 1-input N-output optical switch, and the optical gate switch of the output line from which an optical signal is transmitted is turned on. The optical switch is characterized in that the optical gate switch of the other output line is turned off to prevent passage of an optical signal (crosstalk component). 5. The optical switch according to claim 4, wherein the optical gate switch is turned on when power is applied and turned off when power is not applied. 6. The optical switch according to claim 1 or 2, wherein a wavelength-multiplexed optical signal is input in the preceding stage of the M input ports, the wavelength-division-multiplexed optical signal is demultiplexed for each wavelength, and M number of inputs are input. An optical switch comprising a 1-input M-output optical signal demultiplexer for inputting to each port.