JPH0462650B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention has a plurality of input and output ports, and selectively outputs light (signal light) input from the input port from the output port. The present invention relates to a structured optical matrix switch.

(Prior Art) In recent years, research has been actively conducted on optical switching communication paths in order to increase the speed and bandwidth of information transmission.
Various optical matrix switches have been proposed for configuring this optical switching communication path.

A conventional optical matrix switch will be described below with reference to the drawings.

Figure 12 shows the first conventional optical matrix switch (Reference: Institute of Electronics and Communication Engineers Technical Research Report vol.
SE86-3, p13) is an overall perspective view schematically showing a configuration example.

In the figure, 11 indicates a substrate, and the material of this substrate 11 is a material having an electro-optic effect and suitable for forming an optical switch, such as LiNbO ₃ , InP,
GaAs is used. 13 indicates a 2×2 optical switch element, and 16 optical switch elements 13 are connected to 4
4×4 arranged in rows and 4 columns and provided on the substrate 11
It constitutes an optical matrix switch.

Reference numerals 15 and 17 indicate waveguides for coupling the optical switch elements 13 to each other. As shown in the figure, adjacent optical switch elements 13 in the four optical switch elements 13 in the same row are coupled via waveguides 15 (waveguides 15 are shown by dotted lines in the figure). Furthermore, four optical switch elements 13, one selected from each row and arranged in mutually different columns, are coupled via a waveguide 17 (the waveguide 17 is shown by a solid line in the figure).

19a to 19d are input ports and 21a to 21
d indicates an output port. As shown in the figure, the four optical switch elements 13 in the leftmost column and the input ports 19a-
19d are respectively coupled via waveguides 17, and the four optical switch elements 13 in the rightmost column and output ports 21a to 21d are coupled via waveguides 17.

By the way, in an optical matrix switch with the simplest square lattice configuration, in which adjacent optical switch elements in the same row are coupled together and adjacent optical switch elements in the same column are coupled together, the signal input from the input port is The number of optical switch elements through which light passes (number of passing switch elements) increases or decreases depending on which output port the signal light is output from. On the other hand, in the first conventional optical matrix switch described above, no matter which output port the signal light is output from, the number of passing switch elements is always constant (always four in the illustrated example), and moreover, it has the simplest configuration. This is approximately half the maximum number of passing switch elements in an optical matrix switch.

Therefore, compared to the simplest optical matrix switch constructed using the same number of optical switch elements, the first conventional optical matrix switch can reduce and equalize optical loss and crosstalk. There were advantages.

Next, a second optical matrix switch with a conventional configuration (Reference: Institute of Electronics and Communication Engineers Technical Research Report vol. SE86-4,
p19).

FIG. 13A is an overall perspective view schematically showing a configuration example of a second conventional optical matrix switch;
13B is a diagram schematically showing the mutual coupling state of optical switch elements in the second conventional optical matrix switch shown in FIG. 13A. still,
Components that are the same as those shown in FIG. 12 are designated by the same reference numerals.

As shown in FIG. 13A, the first layer optical switch element group and the second layer optical switch element group each consist of 16 optical switch elements 13 arranged in 4 rows and 4 columns.

In each element group and element group, adjacent optical switch elements 13 in the same row are coupled via a waveguide 23 (the waveguide 23 is shown by a solid line in the figure). As a result, a 1.times.4 optical switch is constructed for each row of the device group, and a 4.times.1 optical switch is constructed for each row of the device group.

Furthermore, the four optical switch elements 13 arranged in the leftmost column of the element group are coupled to the input ports 19a to 19d via waveguides 23, respectively, and the four optical switch elements 13 arranged in the rightmost column of the element group Element 1
3 are respectively coupled to output ports 21a to 21d via waveguides 23.

In addition, as shown in FIG. 13B, four optical switch elements 13 arranged in one row in the element group
and four optical switch elements 13 selected one by one from each row of the element group without overlap.
waveguide 25 (in the figure, waveguide 25
(indicated by a dashed line). In this way, the element groups are combined to form a 4.times.4 optical matrix switch.

As shown in FIG. 13B, in this second conventional optical matrix switch, only one signal light (the signal light is indicated by an arrow in the figure) is input to each optical switch element 13. This has the advantage that almost no crosstalk occurs.

(Problems to be Solved by the Invention) However, in the optical matrix switch of the first conventional configuration described above, for example, as shown by the solid line arrow α and the broken line arrow β in FIG. Depending on the propagation path, two signal lights may be simultaneously input to one optical switch element, so it has not been possible to sufficiently reduce crosstalk in practice.

Furthermore, in the optical matrix switch having the second conventional configuration, the number of optical switch elements required to construct a two-layer optical switch element group increases, for example, n×n.
When constructing an optical matrix switch, the number of optical switch elements is 2n ² , which is twice as many as the number n ² of the optical matrix switch of the first conventional configuration.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional optical matrix switch described above and to provide an optical matrix switch having a structure that can reduce crosstalk.

(Means for Solving the Problems) In order to achieve this object, n optical matrix switches of the present invention (n is an even number and n
≧4) input port side optical switches, first layer and second layer sub optical matrix switches, and n output port side optical switches, each sub optical matrix switch has n/2 It has n/2 first optical switches and n/2 second optical switches.

Regarding the first layer sub-light matrix switches, each light switch is coupled as described below.
That is, two input port-side optical switches are coupled to each first optical switch of the sub-optical matrix switch in the first layer. Further, two output port side optical switches are coupled to each second optical switch of the sub-optical matrix switch in the first layer. Then, all the second optical switches of the sub-light matrix switch are coupled to each first optical switch of the sub-light matrix switch of the first layer.

Furthermore, regarding the second layer sub optical matrix switches, each optical switch is coupled as described below. That is, two input port side optical switches are coupled to each first optical switch of the second layer sub-optical matrix switch. Further, two output port side optical switches are coupled to each second optical switch of the second layer sub-optical matrix switch. Then, all the second optical switches of the secondary optical matrix switch are coupled to each first optical switch of the secondary optical matrix switch of the second layer.

(Function) According to the optical matrix switch of the present invention having such a configuration, two input port side optical switches are installed in each of the first optical switches provided in the first layer and second layer sub optical matrix switches. At the same time, two output port side optical switches are connected to the second optical switches provided in the first and second layer sub-optical matrix switches. Therefore, as a propagation path of light from a predetermined input port of the optical matrix switch of the invention to a predetermined output port of the optical matrix switch of the invention, the first
There are two paths, one comprising a sub-layer optical matrix switch and the other comprising a second-layer sub-optical matrix switch.

Therefore, when propagating signal light from a desired input port to a desired output port of the optical matrix switch of the present invention, any sub-optical matrix switch can be selected.

Therefore, even if two signal lights are input to one optical switch element at the same time in a certain sub-optical matrix switch, it is possible to avoid this by passing them through another sub-optical matrix switch. Signal light can be output.

(Embodiments) Hereinafter, embodiments of the optical matrix switch of the present invention will be described with reference to the drawings. It should be noted that the drawings are merely shown schematically to the extent that the present invention can be understood, and therefore the number of each component, arrangement relationship,
The dimensions and shapes are not limited to the illustrated examples. Further, the same constituent components as those shown in FIG. 12 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

First Embodiment An example in which the present invention is applied to a 4×4 optical matrix switch will be described with reference to FIGS. 1A and 1B.

FIG. 1A is an overall perspective view showing the structure of a first embodiment of the optical matrix switch of the present invention.

In the figure, 31a to 31d indicate input port side optical switches (in the figure, the optical switches 31a to 31d are indicated by dots in white circles), and 33a to 33
d indicates an optical switch on the output port side (optical switches 33a to 33d are indicated by black circles in the figure).

In the illustrated example, four input port side optical switches 3
1a to 31d are individually coupled to input ports 19a to 19d via waveguides, and four output port side optical switches 33a to 33d are individually coupled to output ports 21a to 21d via waveguides. ing.

35a, 35b and 37a, 37b are input port side optical switches 31a to 3, as will be detailed later.
1d, and 3
9a, 39b and 41a, 41b are output port side optical switches 33a to 33d as will be detailed later.
A second light switch is shown coupled to the second light switch.

Further, 43 and 45 indicate sub-light matrix switches. In the illustrated example, the sub light matrix switch 43 of the first layer is composed of two first light switches 35a, 35b and two second light switches 39a, 39b, which are shown as white circles with diagonal lines in the figure. Second
The sub-light matrix switches 45 of the layer are two first light switches 37a, 37b and 2, indicated by white circles in the figure.
It is composed of second optical switches 41a and 41b.

In this embodiment, each of the above-mentioned optical switches 31a-
41b is composed of 2×2 optical switch elements as in the conventional case, and is arranged in 4 rows and 4 columns on the substrate 11.

Next, referring to FIG. 1B, each optical switch 31a
~41b The mutual connection state will be explained in detail. Here, FIG. 1B is a diagram schematically showing the mutual coupling state of the optical switches in the optical matrix switch shown in FIG. 1A. Although the arrangement of the optical switches is different between FIG. 1A and FIG. 1B, the mutual coupling relationship between the optical switches is the same.

Regarding the sub optical matrix switch 43 in the first layer, each optical switch is coupled (connected) as described below via a waveguide shown by a dotted line in the figure.

That is, two input port side optical switches are coupled to each of the first optical switches 35a and 35b provided in the first layer sub-optical matrix switch 43. Specifically, two input port side optical switches 31a and 31b are coupled to a first optical switch 35a, and another two input port side optical switches 31c and 31 are coupled to another first optical switch 35b.
d, and the input port side optical switch connected to the first optical switch 35a is made different from the input port side optical switch connected to the first optical switch 35b.

Further, two output port side optical switches are coupled to each of the second optical switches 39a and 39b provided in the first layer sub-optical matrix switch 43. Specifically, two output port side optical switches 33a and 33b are coupled to a second optical switch 39a, and another two output port side optical switches 33c and 33d are coupled to another second optical switch 39b.
The output port side optical switch connected to the second optical switch 39a and the output port side optical switch connected to the second optical switch 39b are made different.

And the first layer sub-light matrix switch 43
All the second optical switches 3 of the switch 43 are connected to the first optical switches 35a and 35b provided in the switch 43, respectively.
Join 9a and 39b. Furthermore, by coupling the first and second optical switches in this way, the first layer sub-optical matrix switch 43 is constructed, which constitutes a non-blocking network for the two signal lights.

Here, a non-blocking network is one that can connect input ends and output ends of all possible combinations, and that can connect all new additional connections between unused input ends and output ends that are not necessarily unused. A network that can provide connections without regard to other connections that are already in use. In other words, a non-blocking network is one that satisfies every new valid connection request by providing a path for that request without disrupting other already existing connections in the network. It is a network that allows you to

Since the sub-optical matrix switch 43 constitutes a non-blocking network, the propagation path of the signal light can be arbitrarily set between all combinations of input ports and output ports in the switch 43. . Moreover, when two signal lights are simultaneously input to the sub-light matrix switch 43, the propagation paths of each signal light can be set so that the two signal lights do not pass through the same propagation path.

Furthermore, the second layer sub-light matrix switch 45
Regarding this, each optical switch is coupled (connected) as described below via a waveguide shown by a solid line in the figure.

That is, two input port side optical switches are coupled to each of the first optical switches 37a and 37b of the second layer sub-optical matrix switch 45. Specifically, input port side optical switches 31a, 31b are connected to the first optical switch 37a, and input port side optical switches 31c, 31b are connected to the first optical switch 37b.
31d, and these first optical switches 37a,
The input port side optical switch connected to 37b is different. When combined in this way, the common 2
an input group formed by coupling a first optical switch 35a of a first layer and a first optical switch 37a of a second layer to input port side optical switches 31a and 31b;
Two common input port side optical switches 31c, 3
1d and another input group formed by combining the first optical switch 35d of the first layer and the first optical switch 37b of the second layer, two sets of input groups are formed.

Further, each of the second optical switches 41a and 41b of the second layer sub-light matrix switch 45 has two
Connect the output port side optical switches one by one. Specifically, the output port side optical switches 33a and 33b are connected to the second optical switch 41a, and the second optical switch 4
Output port side optical switches 33c and 33d are coupled to 1b, and different output port side optical switches are coupled to these second optical switches 41a and 41b.
In such a case, the second optical switch 39a in the first layer and the second optical switch 4 in the second layer are connected to the two common output port side optical switches 33a and 33b.
1a and the common output group 2a.
There are two sets of output groups, including another output group formed by coupling the second optical switch 39b of the first layer and the second optical switch 41b of the second layer to the output port side optical switches 33c and 33d. To form and to become.

And the second layer sub-light matrix switch 45
to each of the first light switches 37a, 37b,
All second light switches 41 of the switch 45
Combine a and 41b. Moreover, by coupling the first and second optical switches in this manner, the second layer sub-optical matrix switch 45 is constructed, which constitutes a non-blocking network for the two signal lights.

Since the sub-optical matrix switch 45 constitutes a non-blocking network, the propagation path of the signal light can be arbitrarily set between all combinations of input ports and output ports in the switch 45. . Moreover, when two signal lights are simultaneously input to the sub-light matrix switch 45, the propagation paths of the respective signal lights can be set so that the two signal lights do not pass through the same propagation path.

In addition, when the waveguides are provided on the substrate 11, the crossing angle of the waveguides that intersect with each other should be at least 2 degrees or more so that crosstalk can be suppressed to a minimum in practical terms.
It is preferable to design it so that it has an angle of about 3° or more.

Next, the operation of the optical matrix switch of this embodiment will be explained. Therefore, as an example, the signal light a input from the input port 19a and the signal light c input from the input port 19c are sent to one of the output ports 21a to 21d via the second layer sub-optical matrix switch 45. We will mainly consider the case where the output is output to . In the following description, signal b indicates signal light input to input port 19b, and signal light d indicates signal light input to input port 19d. In addition, input port side optical switches 31a to 3
1d operates so that only two signal lights are input to each of the sub-optical matrix switches 43 and 45.

[1] When outputting signal light a from output port 21a (a) When outputting signal light c from output port 21c or 21d The first operation example will be explained below with reference to FIGS. 2A to C. .

As shown in FIG. 2A, signal light a is output from output port 21a via optical switches 31a, 37a, 41a, and 33a. The signal light c is transmitted through optical switches 31c, 37b, 41b, 3
3c from the output port 21c or the optical switches 31c, 37b, 41b, 3
The signal is output from the output port 21d via the signal line 3d.

At this time, consider the case where the signal light b is output from the output port 21b as shown in FIG. 2B.

As shown in the figure, the signal light b is transmitted to the optical switch 31
It is output from the output port 21b via the ports 21b, 35a, 39a, and 33b. When the signal light c is output from the output port 21c, the signal light d is transmitted to the optical switches 31d, 35b, 39b, and 33d.
or if the signal light c is output from the output port 21d, the optical switches 31d, 35b, 39b, 3
3c and is output from the output port 21c.

Also, consider the case where the signal light b is output from the output port 21c or 21d, as shown in FIG. 2C.

Signal light b is output port 21c, and signal light c is output port 21c.
If the output is from the optical switches 31b and 35
Output port 21 via a, 39b, 33d
If the signal light c is output from the output port 21d, the optical switch 31b,
It is output from the output port 21d via 35a, 39b, and 33d. Signal light d is output from output port 21d via optical switches 31d, 35b, 39a, and 33b.

As is clear from the figure, in this first operation example, each of the signal lights a to d is output through separate paths, so two signal lights will not be input to one optical switch element at the same time.

(b) When outputting the signal light c from the output port 21b A second operation example will be described below with reference to FIGS. 3A and 3B.

As shown in FIG. 3A, signal light c is output from output port 21b via optical switches 31c, 37b, 41a, and 33b.

At this time, consider the case where the signal light b is output from the output port 21c or 21d, as shown in FIG. 3B.

As shown in the figure, the signal light b is transmitted to the optical switch 31
b, 35a, 39b, 33c from the output port 21c or the optical switch 31.
b, 35a, 39b, and 33c from the output port 21c.

The signal light d is output to the output port 21c.
If it is output from the optical switch 31d, 35
Output port 21 via b, 39b, 33b
If the signal light b is output from the output port 21d, the optical switch 31d,
It is output from the output port 21d via 35b, 39b, and 33b.

As is clear from FIGS. 3A and 3B, in this second operation example, signal lights a and c are simultaneously input to the optical switch 41a, and signal lights b and d are simultaneously input to the optical switch 39b. This causes a malfunction due to crosstalk.

However, in this case, as shown in FIGS. 4A and 4B, the optical switch 31d is operated to input the signal light d to the second layer sub optical matrix switch 45, and the optical switch 31c is operated to input the signal light d. It is sufficient to input the light c to the sub-light matrix switch 43 of the first layer. The operation in this case (third operation example) will be described below with reference to FIGS. 4A and 4B.

As shown in FIG. 4A, the signal light d is transmitted to the optical switches 31d, 35b, 39b, 41b, 3
3c from the output port 21c or optical switches 31d, 37b, 41b, 33
It is configured to output from the output port 21d via. When the signal light b is output from the output port 21c, the signal light b is output from the optical switch 31d,
35a, 39b, 33b from the output port 21d, or if the signal light d is output from the output port 21d, the optical switch 31
b, 35a, 39b, and 33c from the output port 21c.

As in this third operation example, the input port side optical switches 31c and 31d are operated to select the sub-optical matrix switch 43 or 45 to which the signal lights c and d are input, so that the signal lights are Simultaneous input to one optical switch element can be avoided. Therefore, crosstalk can be reduced.

As shown in FIG. 4B, even if the signal lights b and c intersect, by setting the intersection angle of the waveguides to at least 2° to 3°, the signal lights b and c will not intersect. The black talk caused by this can be suppressed to a sufficiently low level for practical purposes.

[2] When outputting signal light a from output port 21c (a) When outputting signal light c from output port 21a or 21b The fourth operation example will be explained below with reference to FIGS. 5A to 5C. .

As shown in FIG. 5A, signal light a is output from output port 21c via optical switches 31a, 37a, 41b, and 33c. The signal light c is transmitted through optical switches 31c, 37b, 41a, 3
3a from the output port 21a or optical switches 31c, 37b, 41a, 3
The signal is output from the output port 21b via the signal line 3b.

At this time, consider the case where the signal light b is output from the output port 21a or 21b, as shown in FIG. 5B.

As shown in the figure, the signal light b is transmitted to the optical switch 31
b, 35a, 39a, 33a from the output port 21a or the optical switch 31.
It is output from the output port 21b via the ports 21b, 35a, 39a, and 33b.

Signal light b is output port 21a, and signal light c is output port 21a.
If the signal light c is output from the output port 21b, it is output from the output port 21b, or if the signal light c is output from the output port 21b, it is output from the output port 21a. The signal light d is transmitted through optical switches 31d, 35b,
It is output from the output port 21d via 39b and 33d.

Also, consider the case where the signal light b is output from the output port 21d, as shown in FIG. 5C.

As shown in the figure, the signal light b is transmitted to the optical switch 31.
It is output from the output port 21d via the ports 21d, 35a, 39b, and 33d.

The signal light d is output from the output port 21a.
If the output is output from the optical switches 31d and 35
Output port 21 via b, 39a, 33b
If the signal light c is output from the output port 21b, the optical switch 31
It is output from the output port 21a via d, 35b, 39a, and 33a.

As is clear from the figure, in this fourth operation example, each of the signal lights a to d is output through separate paths, so two signal lights will not be input to one optical switch element at the same time.

(b) When outputting the signal light c from the output port 21b A fifth operation example will be described below with reference to the drawings.

As shown in FIG. 6A, the signal light c is output from the output port 21d via optical switches 31c, 37b, 41b, and 33d.

At this time, consider the case where the signal light b is output from the output port 21a or 21b, as shown in FIG. 6B.

As shown in the figure, the signal light b is transmitted to the optical switch 31
b, 35a, 39a, 33a from the output port 21a or the optical switch 31.
It is output from the output port 21b via the ports 21b, 35a, 39a, and 33b.

The signal light d is output from the output port 21a.
If it is output from the optical switch 31d, 35
Output port 21 via b, 39a, 33b
If the signal light b is output from the output port 21b, the optical switch 31d,
It is output from the output port 21a via 35b, 39a, and 33a.

As is clear from FIGS. 6A and 6B, in this fifth operation example, signal lights a and c are simultaneously input to the optical switch 41b, and signal lights b and d are simultaneously input to the optical switch 39a. This causes a problem of crosstalk.

However, in this case, as shown in FIGS. 7A and 7B, the optical switch 31d is operated to input the signal light d to the second layer sub optical matrix switch 45, and the optical switch 31c is operated to input the signal light d. It is sufficient to input the light c to the sub-light matrix switch 43 of the first layer. below,
The operation in this case (sixth operation example) will be explained with reference to FIGS. 7A and 7B.

As shown in FIG. 7A, the signal light d is output from the output port 21a via the optical switches 31d, 37b, 41a, and 33a, or from the output port 21a via the optical switches 31d, 37b, 41a, and 33a. Make it output. Signal light b and signal light d are connected to output port 21
If the output is from a, the optical switches 31b and 35
Output port 21 via a, 39a, 33b
If the signal light d is output from the output port 21b, the optical switch 31b,
It is output from the output port 21a via 35a, 39a, and 33a.

In this way, in the sixth operation example, by operating the input port side optical switches 31c and 31d and selecting the sub optical matrix switch 43 or 45, two signal lights are transferred to one optical switch element. You can avoid inputting both at the same time. Therefore, crosstalk can be reduced.

As shown in FIG. 7A, even if the signal lights a and d intersect, by setting the intersection angle of the waveguide to at least 2° to 3°, the signal lights a and d will not intersect. The crosstalk caused by this can be suppressed to a sufficiently low level for practical purposes.

[3] When outputting signal light a from output port 21b (a) When outputting signal light c from output port 21c or 21d The seventh operation example will be described below with reference to FIG. 8. As shown in FIG. 8, signal light a is transmitted to optical switches 31a, 37a, 41a, 33b.
The signal is outputted from the output port 21b via the output port 21b.

In this case, the waveguide 47 and the waveguide 49 in FIG. 2A are exchanged, and the waveguide 47 and the waveguide 49 in FIG.
This can be considered to be equivalent to the case where the waveguide 51 and the waveguide 53 are replaced in the case of . Therefore, in the seventh operation example, each of the signal lights a to d is output through separate paths, so two signal lights will not be input to one optical switch element at the same time.

Note that the waveguide 47 is a waveguide formed between the optical switch 41a and the optical switch 33a, the waveguide 49 is a waveguide formed between the optical switch 41a and the optical switch 33b, and the waveguide 51 is a waveguide formed between the optical switch 41a and the optical switch 33b.
indicates a waveguide formed between optical switch 39a and optical switch 33a, and waveguide 53 indicates a waveguide formed between optical switch 39a and optical switch 33b.

(b) When outputting the signal light c from the output port 21a In this case, it is equivalent to replacing the waveguides 47 and 49 in FIG. 3A and replacing the waveguides 51 and 53 in FIG. 3B. (eighth operation example).

Therefore, in the eighth operation example, the optical switch 39a
The signal lights a and c are connected to the optical switch 3.
Since the signal lights b and d are input at the same time at 9b, this causes a problem in that crosstalk occurs.

However, in this case, the waveguides 47 and 49 in FIG.
It is sufficient to consider this in the same manner as when the waveguides 51 and 53 are exchanged in FIG. B (ninth operation example).
That is, the input port side optical switch 31c,
31d is operated to switch the sub optical matrix switch 43 or 4 to which the signal lights c and d are input.
By making the selection No. 5, it is sufficient to avoid inputting two signal lights to one optical switch element at the same time.

[4] When outputting signal light a from output port 21d (a) When outputting signal light c from output port 21a or 21b The tenth operation example will be described below. As shown in FIG. 9, the signal light a is transmitted to the optical switch 31.
A, 37a, 41b, and 33d are outputted from the output port 21d.

In this case, the waveguides 55 and 57 in FIG. 5A are interchanged, and the waveguides 55 and 57 in FIG.
This can be considered to be equivalent to the case where the waveguides 59 and 61 are interchanged. Therefore, in the tenth operation example, since each of the signal lights a to d is output through separate paths, two signal lights will not be input to one optical switch element at the same time.

Note that the waveguide 55 is a waveguide formed between the optical switch 41b and the optical switch 33c, the waveguide 57 is a waveguide formed between the optical switch 41b and the optical switch 33d, and the waveguide 59 is a waveguide formed between the optical switch 41b and the optical switch 33d.
indicates a waveguide formed between optical switch 39b and optical switch 33c, and waveguide 61 indicates a waveguide formed between optical switch 39b and optical switch 33d.

(b) When outputting the signal light c from the output port 21c The waveguides 55 and 57 in FIG. 6A are interchanged, and the waveguide 5 in FIG.
This can be considered equivalent to the case where 9 and 61 are exchanged (eleventh operation example).

Therefore, in the eleventh operation example, the optical switch 41
Since the signal lights a and c are input at the same time at the optical switch 39a, and the signal lights b and d are input at the same time at the optical switch 39a, this causes a problem in that crosstalk occurs.

However, in this case, it is sufficient to consider the same case as replacing the waveguides 55 and 57 in FIG. 7A and replacing the waveguides 59 and 61 in FIG. 7B (twelfth operation example). That is, by operating the input port side optical switches 31c and 31d and selecting the sub optical matrix switch 43 or 45 to which the signal lights c and d are input,
It is sufficient to avoid inputting signal lights to one optical switch at the same time.

In addition, in the explanation of the operation example of the first embodiment mentioned above, all the combinations of the passage ports (input ports and output ports) of the signal lights a to d in the 4x4 optical matrix switch are covered (24 combinations in total). combination).

As described above, according to the first embodiment, crosstalk can be reduced more than in the first conventional optical matrix switch. Also,
The number of optical switch elements required to configure the optical matrix switch of the first embodiment is 16, which is less than the number of optical switch elements required to configure the optical matrix switch of the second conventional configuration. .

Second Embodiment An example in which the present invention is applied to an 8.times.8 optical matrix switch will be described with reference to FIGS. 10A to 10C.

FIG. 10A is an overall perspective view schematically showing the configuration of the second embodiment.

In the same figure, 71 is an input port side optical switch coupled to first optical switches 81 and 87 (in the figure, this optical switch 71 is shown with a dot in a white circle), and 75 is a light switch connected to first optical switches 81 and 87, as will be described later. An output port side optical switch (the optical switch 75 is indicated by a black circle in the figure) coupled to the second optical switches 83 and 89 is shown.

In the illustrated example, eight input port side optical switches 7
One input port 73 is coupled to each of the input ports 1 through a waveguide. In addition, one output port 7 is provided for each of the eight output port side optical switches 75.
7 are coupled via a waveguide. In this embodiment, the input port side optical switch 71 and the output port side optical switch 75 are each constituted by one 2.times.2 optical switch element.

Further, 79 and 91 indicate sub-light matrix switches. In the illustrated example, the first layer sub-light matrix switch 79 consists of four first optical switches 81 and four second optical switches 83, and the second layer sub-light matrix switch 91 consists of four first optical switches 81 and four second optical switches 83. It consists of a first optical switch 87 and four second optical switches 89. The first light switch 81 and the second light switch 83 are shown as open squares in the figure, and the first light switch 87 and the second light switch 89 are shown as squares with diagonal lines in the figure.

Next, referring to FIG. 10B, the first optical switches 81, 87 and the second optical switches 83, 8 of this embodiment are explained.
The configuration of No. 9 will be explained.

In the same figure, 97 is the first optical switch 81, 8
7 or an optical switch used as the second optical switch 83, 89, 93 represents a 2×2 optical switch element, and 95 represents a 2×1 optical switch element.

As shown in the figure, the optical switch 97 consists of two optical switch elements 93 and two optical switch elements 95, and two optical switch elements 95 are coupled to each of the optical switch elements 93 via a waveguide. The structure is as follows. The optical switch 97 operates as a 2×4 optical switch when used as the first optical switches 81 and 87 in the illustrated example, and operates as a 4×2 optical switch when used as the second optical switches 83 and 89 in the illustrated example. It works as.

Next, the mutual coupling state of each optical switch will be explained.

Regarding the sub-optical matrix switch 79 in the first layer, each optical switch is coupled to a waveguide as described below.

That is, as shown in FIG. 10A, two input port side optical switches 71 are coupled to each of the first optical switches 81 provided in the first layer sub-optical matrix switch 79. Each first light switch 8
The input port side optical switch 79 connected to the input port 1 is made different.

Further, two output port side optical switches 75 are coupled to each of the second optical switches 83 provided in the first layer sub-optical matrix switch 79. The output port side optical switches 75 coupled to each second optical switch 83 are made different.

Then, as shown in FIG. 10C, all the second optical switches 83 of the first layer sub-optical matrix switch 79 are coupled to the first optical switch 81 of the sub-optical matrix switch 79, respectively. In the figure, a group q formed by connecting all the second optical switches 83 to one first optical switch 81 is shown surrounded by a dashed-dotted line with the symbol q. Moreover, by coupling the first and second optical switches in this manner, the first layer sub-optical matrix switch 79 is constructed, which constitutes a non-blocking network for four signal lights.

Since the sub-optical matrix switch 79 constitutes a non-blocking network, the propagation path of the signal light can be arbitrarily set between all pairs of input ports and output ports that can be combined in the sub-optical matrix switch 79. Moreover, when four signal lights are simultaneously input to the sub-light matrix switch 79, four
The propagation path of each signal light can be set so that two signal lights do not pass through the same propagation path.

Furthermore, the second layer sub-light matrix switch 91
Regarding this, each optical switch is coupled via a waveguide as described below.

That is, as shown in FIG. 10A, two input port side optical switches 71 are coupled to each of the first optical switches 87 of the second layer sub-optical matrix switch 91. The input port side optical switches 71 coupled to each first optical switch 87 are made different. In addition, four input groups p are formed by connecting one first optical switch 81 of the first layer and one first optical switch 87 of the second layer to the two common input port side optical switches 71. do. In the figure, one input group p is shown surrounded by a dashed-dotted line with the symbol p.

Further, two output port side optical switches 75 are coupled to each second optical switch 89 of the second layer sub-optical matrix switch 91. Output port side optical switch 7 coupled to each second optical switch 89
5 different. Moreover, the second optical switch 8 of the first layer is connected to the two common output port side optical switches 75.
3 and a second optical switch 89 of the second layer are combined to form four output groups r. In the figure, one set of output groups r is shown surrounded by a dashed line with the symbol r.

Then, as shown in FIG. 10C, all the second optical switches 89 of the switch 91 are coupled to the second layer sub-light matrix switch 91 and each first optical switch 87, respectively. In the figure, a group q consisting of all the second optical switches 89 connected to one first optical switch 87 is shown surrounded by a dashed-dotted line with the symbol q. Moreover, while coupling the first and second optical switches in this manner, the second layer sub-optical matrix switch 91, which constitutes a non-blocking network for four signal lights, is connected to the first-layer sub-optical matrix switch 91. It is configured in the same manner as 79.

Also in the second embodiment described above, if two signal lights are simultaneously input to one optical switch element in the sub optical matrix switch 79 or 91 of the first layer or the second layer. Also, the propagation path of the signal light can be changed by operating the input port side optical switch 71 and selecting the sub optical matrix switch to which the signal light is input. As a result, as in the first embodiment, it is possible to avoid the case where two signal lights are simultaneously input to one optical switch element, thereby reducing crosstalk. Furthermore, in this embodiment, the number of points at which crosstalk occurs due to two signal lights being input to one optical switch element at the same time is at most 1.
It is a place. Therefore, this embodiment can reduce crosstalk more than the first conventional optical matrix switch.

In addition, the number of optical switch elements required for the configuration of the second embodiment is 80, which is smaller than the optical matrix switch of the second conventional configuration.

Third Embodiment FIGS. 11A to 11C are diagrams for explaining a third embodiment. In the third embodiment, an example in which the present invention is applied to a 16×16 optical matrix switch will be explained.

FIG. 11A is an overall perspective view schematically showing the configuration of the third embodiment.

In the same figure, 201 is an input port side optical switch that is coupled to first optical switches 211 and 217 (in the figure, this optical switch 201 is shown with a dot in a white circle), and 205 is a dotted white circle, which will be described later. The output port side optical switch (optical switch 205 is indicated by a black circle in the figure) which is coupled to the second optical switches 213 and 219 as shown in FIG.

In the illustrated example, 16 input port side optical switches 2
01 is coupled to one input port 203 via a waveguide. At the same time, one output port 207 is coupled to each of the 16 output port side optical switches 205 via a waveguide. In this embodiment, the input port side optical switch 20
1 and the output port side optical switch 205 are each composed of one 2×2 optical switch element.

209 and 221 indicate sub-light matrix switches. In the illustrated example, the first layer sub-light matrix switch 209 is composed of eight first optical switches 211 and eight second optical switches 213, and the second layer sub-light matrix switch 221 is composed of eight first optical switches 211 and eight second optical switches 213. eight first light switches 217 and eight second light switches 2
It consists of 19. The first light switch 211 and the second light switch 213 are shown as open squares in the figure, and the first light switch 217 and the second light switch 219 are shown as squares with diagonal lines in the figure.

Next, with reference to FIG.
The configuration of No. 3,219 will be explained.

In the figure, 223 is the first optical switch 21
1, 217 or a second optical switch 213, 219 is shown. In the illustrated example, the optical switch 223 is connected to two optical switches 9
7 and two 2×1 optical switch elements 96.

That is, in the optical switch 223, one optical switch element 96 is coupled to each of the optical switch elements 95 constituting the optical switch 97 via a waveguide and engaged with the two optical switches 97. At the same time, the other optical switch element 96 is connected to the other optical switch element 9 constituting the optical switch 97.
5 through waveguides, and then to two optical switches 97.

The optical switch 223 configured in this manner operates as a 2×8 optical switch when used as the optical switches 211 and 217, and operates as a 2×8 optical switch when used as the second optical switch 213 and 219.
Operates as a ×2 optical switch. Therefore, the sub-light matrix switches 209 and 221 constitute a 16.times.16 light matrix switch.

Next, the mutual coupling state of each optical switch will be explained.

Regarding the first layer sub-optical matrix switch 209, each optical switch is coupled via a waveguide as described below.

That is, as shown in FIG. 11A, two input port side optical switches 201 are coupled to each of the first optical switches 211 provided in the first layer sub-optical matrix switch 209. Input port side optical switch 2 coupled to each first optical switch 211
01 are different.

In addition, the first layer sub-light matrix switch 209
Two output port-side optical switches 205 are coupled to each of the second optical switches 213 provided in the second optical switch 213 .
The output port side optical switches 205 coupled to each second optical switch 213 are made different.

Then, as shown in FIG. 11C, all the second optical switches 213 of the first layer sub-optical matrix switch 209 are coupled to the first optical switch 211 of the sub-optical matrix switch 209, respectively. In the figure,
A group t formed by connecting all the second optical switches 213 to one first optical switch 211,
It is shown surrounded by a dashed dotted line with the symbol t. Moreover, while coupling the first and second optical switches in this way, the first layer sub optical matrix switch 209 constitutes an optical blockage network for eight signal lights.
Configure.

Since the sub-optical matrix switch 209 constitutes a non-blocking network, the propagation path of the signal light can be arbitrarily set between all pairs of input ports and output ports that can be combined in the switch 209. . Furthermore, when eight signal lights are simultaneously input to the sub-light matrix switch 209, the propagation paths of each of the signal lights can be set so that the eight signal lights do not pass through the same propagation path.

Furthermore, the second layer sub-light matrix switch 22
1, each optical switch is coupled via a waveguide as described below.

That is, as shown in FIG. 11A, two input port side optical switches 201 are coupled to each of the first optical switches 217 of the second layer sub-optical matrix switch 221. Each first light switch 2
The input port side optical switch 201 coupled to the input port 17 is made different. Moreover, the first optical switch 21 of the first layer is connected to the common two input port side optical switches 201.
Eight input groups s are formed by combining one optical switch 1 and the first optical switch 217 of the second layer.
In the figure, one set of input groups s is shown surrounded by a dashed-dotted line with the symbol s.

In addition, the second layer sub-light matrix switch 221
Two output port side optical switches 205 are coupled to each of the second optical switches 219 . The output port side optical switches 205 coupled to each second optical switch 219 are made different. Moreover, the second optical switch 213 of the first layer and the second optical switch 21 of the second layer are connected to the common two output port side optical switches 205.
The output group u formed by combining 9 and 9 one by one is
Form 8 groups. In the figure, one output group u is shown surrounded by a dashed-dotted line with the symbol u.

Then, as shown in FIG. 11C, all the second optical switches 219 of the second-layer sub-light matrix switch 221 are coupled to each first optical switch 217 of the second-layer sub-light matrix switch 221, respectively. In the figure, a group t formed by connecting all the second optical switches 219 to one first optical switch 217 is surrounded by a chain line with the symbol t. Moreover, while combining the first and second light switches in this way, the 8
The secondary optical matrix switch 221 of the second layer, which constitutes a non-blocking network for two signal lights, is connected to the first
The structure is similar to that of the sub-light matrix switch 209 of the layer.

Also in the third embodiment described above, the sub-light matrix switch 209 or 22 of the first layer or the second layer
In step 1, even if two signal lights are input to one optical switch element at the same time, the input port side optical switch 201 is operated to select the sub-optical matrix switch to which the signal light is input. By doing so, the propagation path of the signal light can be changed. As a result, as in the first embodiment, crosstalk can be reduced more than in the optical matrix switch of the first conventional configuration.

In addition, the number of optical switch elements required for the configuration of the third embodiment is 352, which is smaller than the optical matrix switch of the second conventional configuration.

The present invention is not limited to the embodiments described above, and various changes can be made depending on the design. For example, the number of the first optical switch, sub-light matrix switch, and other constituent components may be set arbitrarily, and the number of optical switch elements constituting each constituent component may also be arbitrarily set depending on the design. Alternatively, the coupling state between the first optical switch and the input port side optical switch and the coupling state between the second optical switch and the output port side optical switch may be arbitrarily set according to the design.

Further, as a light propagation path from the input port to the output port of the optical matrix switch of the present invention, a path including a first layer sub-optical matrix switch and a path including a second layer sub-optical matrix switch are provided. If it is possible to configure two systems with
The arrangement method of these sub-light matrix switches does not matter; therefore, for example, the sub-light matrix switches of the first layer and the second layer may be provided on the same substrate surface, or the sub-light matrix switches of the first layer The optical matrix switch and the secondary optical matrix switch of the second layer may be stacked so as to overlap each other, or the optical matrix switch of the second layer may be stacked.
The second layer and second layer sub-light matrix switches may be provided separately on different substrates.

Further, the present invention may be applied to an n×n optical matrix switch (where n is an even number and n≧4).

(Effects of the Invention) As is clear from the above description, the optical matrix switch of the present invention avoids the case where two signal lights are simultaneously input to one optical switch element, and Crosstalk can be reduced more than the optical matrix switch of conventional configuration.

[Brief explanation of drawings]

Figures 1A and 1B are diagrams for explaining the configuration of the first embodiment, Figures 2 to 9 are diagrams for explaining the operation of the first embodiment, and Figures 10A to C are diagrams for the second embodiment. 11A to 11C are diagrams showing the configuration of the third embodiment. FIG. 12 is a diagram showing the configuration of the first conventional optical matrix switch. FIGS. 13A and B are diagrams showing the configuration of the optical matrix switch of the first conventional configuration. FIG. 7 is a diagram for explaining the configuration of a second conventional optical matrix switch. 11...Substrate, 19a to 19d, 73, 203
...Input ports, 21a to 21, 77, 207...
...Output port, 31a to 31d, 71, 201...
...Input port side optical switch, 33a to 33d, 7
5,205...Output port side optical switch, 35
a, 35b, 37a, 37b, 81, 87, 21
1,217...Daiichi light switch, 39a, 39
b, 41a, 41b, 83, 89, 213, 21
9...Second light switch, 43, 45, 79, 9
1,209,221...Sub-light matrix switch.

Claims (1)

[Claims] 1 n input port side optical switches (n is an even number and n≧4), first layer and second layer sub optical matrix switches, and n output port side optical switches. and a switch, and each sub-light matrix switch has n/
It has two first optical switches and n/2 second optical switches, and two input port side optical switches are connected to each first optical switch of the first layer sub-optical matrix switch. , two output port side optical switches are coupled to each of the second optical switches of the sub-optical matrix switches in the first layer, and the corresponding first optical switches are coupled to each of the first optical switches of the sub-optical matrix switches in the first layer. All the second optical switches of the sub-optical matrix switches are coupled, and two input port-side optical switches are coupled to each first optical switch of the sub-optical matrix switch of the second layer. Two output port-side optical switches are coupled to each second optical switch of the sub-optical matrix switch, and the corresponding sub-optical matrix switch is connected to each first optical switch of the second-layer sub-optical matrix switch. An optical matrix switch characterized by combining all of the second optical switches. 2 Connect the first optical switch to the two common input port side optical switches.
n/2 input groups are formed by combining the first optical switches of the sub-optical matrix switches of the second layer and the second layer, one by one, and the first and second optical switches are connected to two common output port side optical switches. An optical matrix switch according to claim 1, characterized in that n/2 output groups are formed by coupling one second optical switch of a two-layer sub-optical matrix switch. . 3. The optical system according to claim 1, wherein the sub optical matrix switches of the first layer and the second layer are optical switches that configure a non-blocking network for n/2 signal lights. Matrix switch.