JPH0545931B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention has a plurality of input ports and output ports, selects a matrix of optical input signals supplied to the input ports, and outputs the optical signals from the output ports. This relates to an optical matrix switch that outputs an output signal.

[Conventional technology]

Recently, with the introduction of optical fibers into transmission systems, research has been actively conducted on the use of waveguide type optical switches in switching equipment as well.

FIG. 2 is a perspective view showing the structure of an optical matrix switch using such a waveguide type optical switch. On a substrate 9 made of LiNbo ₃ having an electro-optic effect, sixteen 2×2 optical switches 91 are arranged in a square lattice of 4 rows and 4 columns. 4 input ports 1
a, 1b, 1c, 1d have 2×2 lines that make up the row.
One input and output of each optical switch 91 are connected in series through a waveguide 93, and the output of the 2×2 optical switch 91 in the last row is connected to four output ports 2a, 2b, 2c, and 2d. It is connected to the. In addition, the output of each 2×2 optical switch 91 that does not form a row is connected to the other input that does not form a row of the adjacent 2×2 optical switch 91 in the subsequent column via a waveguide 93. connected, each 2
The ×2 optical switches 91 are connected to each other diagonally. According to the above conventional technology,
Information input from any of the input ports 1a, 1b, 1c, and 1d is stored in a 2x2 matrix placed at the intersection of the matrix.
An optical switch 91 switches the direction of the outgoing lines into a so-called direct state or a crossing state. and,
Compared to the most basic optical matrix switch, which is constructed by arranging optical switches in rows and columns in a square lattice and orthogonally connecting each optical switch, it is difficult to understand what kind of input is required even though it is composed of the same number of optical switches. The optical switch means that passes through each combination of ports and output ports is always the same, and the number of optical switches is 1/2 compared to the worst case of a basic optical matrix switch. It has the feature of reducing talk.

However, even with the above conventional technology,
Information input from the input port 1b as shown by the solid line arrow in FIG. It had the disadvantage of causing

On the other hand, a perspective view of FIG. 3 shows the structure of an optical matrix switch that has been improved so as not to cause crosstalk. According to the improved prior art,
On the board 9 are input ports 1a, 1b, 1c,
1d, 16 2×2 optical switches 94 arranged in a square grid of 4 rows and 4 columns, and output port 2.
Similar 2x2 connected to a, 2b, 2c, 2d
An optical switch 95 is arranged. The 2×2 optical switches 94 and 95 located at each grid intersection on the input port side and the output port side are arranged so that each row on the output port side is positioned one row at a time for each column on the input port side. and are mutually connected by a waveguide 93.

According to this, since different information is not input to one 2x2 optical switch, the information input to the input port is matrix-selected and output to the output port without causing almost any crosstalk. can do.

However, with the above-mentioned conventional technology, although crosstalk can be significantly reduced compared to an optical matrix switch consisting of 2x2 optical switches arranged in a simple square grid, the input port side Optical switches arranged in a square lattice are required depending on the number of ports, and the same number of optical switches arranged in a square lattice are also required on the output port side. For this reason, twice as many optical switches are required as compared to an optical matrix switch with a simple square lattice arrangement, so the overall size of the optical matrix switch becomes larger. The number of light switch means to do so also increases. Another problem was that light loss could not be reduced.

To solve this problem, the switch can be configured with the same number of optical switches as an optical matrix switch with a simple square lattice arrangement, and the number of stages of optical switches from the input port to the output port is small, making it more compact. The present applicant has proposed an optical matrix switch that can be formed easily and has excellent crosstalk characteristics (Japanese Patent Application No. 267700/1982). The optical matrix switch is as shown in FIGS. 4A and 4B for a 4.times.4 type and an 8.times.8 type optical matrix switch, respectively. That is, in FIG. 4A, 1a to 1d are input waveguides, 5a to 5
d is the output waveguide, 2a to 2d, 4a to 4d are 1×
2x2 type optical switches used as type 2 and 2x1 type, 3a to 3d are 2x2 type optical switches,
The "○" mark indicates an optical switch, and the "-" mark indicates a waveguide connecting the optical switches. These optical switches and waveguides are formed on the same substrate.

In FIG. 4B, 1a to 1h are input waveguides, 5a to 5h are output waveguides, and 2 _1a to 2 _1h
is a 2×2 type optical switch used as a 1×2 type, and 4 _2a to 4 _2h are 2×2 type optical switches used as a 2×1 type.
It is a ×2 type optical switch. Each of 7a to 7d is
This is a 4×4 type optical switch, and consists of a 2×2 optical switch having the structure shown in FIG. 4A. In FIG. 4B, input waveguides 1a to 1h and 1×2 type optical switches 2 _1a to
2 _1h is divided into two groups: those with subscripts a to d and those with subscripts e to h, and the output side 2×1 type optical switches 4 _2a to 4 _2h and the output waveguide 5a. ~5h is also divided into two groups.

Input ports la to ld are selectively connected to one side by 1×2 type optical switches 2 _1a to 2 _1d on the input side to 4×4 type optical switches 7a and 7b connected to two output port groups. Similarly, input ports le to lh are
The 1×2 type optical switches 2 _1a to 2 _1h on the input side allow
It is selectively connected to one of 4×4 type optical switches 7c and 7d connected to two output port groups. On the other hand, the 2×1 type optical switches 4 _2a to 4 _2h on the output side select one of the 4×4 type optical switches 7a, 7b; 7c, 7d connected to the two input port groups la to ld, le to lh. and connect it to the output port. Which output port to select from one group is determined by operating the 4×4 type optical switches 7a to 7d.

This type of optical matrix switch has the major feature of being smaller than the commonly used square lattice type.

[Problem that the invention seeks to solve]

However, the above configuration has the disadvantage that crosstalk characteristics deteriorate due to optical loss occurring at the intersections of the waveguides. For example, in FIG. 4c, the signal light 4 passing through the waveguide 7c-4 _2a
Let's consider 1. Signal light 4 is also connected to waveguide 7a-4 _2b.
2, the waveguides 41 and 42 cross each other at the intersection 43, causing crosstalk. The amount of crosstalk to the waveguides 7c to _42a at the intersection 43 is relative to the amount of signal light 42.
20dB, 44a to 44f, 4 at the intersection
Assume that the loss at 3 is 2 dB. Assuming that the signal lights 41 and 42 have the same light intensity at the beginning, when the signal light 41 passes the intersection 43, it has already passed through the intersections 44a to 44f and 43, so the signal light 41 becomes a signal immediately after the intersection 43. It is 14 dB smaller than the light intensity of light 42. Therefore, the amount of crosstalk with respect to the amount of signal light 41 is
It increases to 6dB.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical matrix switch that can eliminate the above-mentioned drawbacks, improve crosstalk characteristics, and make the output intensity of light uniform.

[Means for solving problems]

In order to achieve the above object, the optical matrix switch according to the present invention branches optical input signals inputted from 2 ⁱ⁺¹ (i is a natural number) input ports into 2 ⁽²ⁱ⁺¹⁾ branch signals. An input branching tree configured with a tree consisting of 1×2 branching means of stages, and an input branching tree connected in series to the input branching tree to form one stage of a duplicate tree configuration, and branched and supplied from different input ports. Input the two types of branch signals,
2i ^2x2 optical switches that select one of the two outputs and output a switch output signal, and the 2x2
Input the switch output signal of the optical switch and
2 It is equipped with an output multiplexing tree configured by a 2×1 multiplexing means of i stage that outputs the optical output signal to the output port of ⁱ⁺¹ , and by providing a dummy intersection, the output from the input port is This is characterized in that the number of intersections is made equal for any light propagation path until reaching the port.

[Effect]

According to the present invention, since the optical matrix switch is configured as described above, the optical input signals supplied to the 2 ^{i +1} input ports are divided into 1×2 demultiplexers of i stages constituting the input demultiplexing tree. The signal is branched into 2 ⁽²ⁱ⁺¹⁾ branch signals by a means, and is supplied to two inputs of 2 ²ⁱ 2×2 optical switches which together with the input branch tree form one stage of an overlapping tree. Either of the branch signals from the different input ports is selected and the two
2 i+1 is output as a switch output signal to one of the outputs, and is outputted as a switch output signal to 2 ⁱ⁺¹
The output signal is branched and supplied to the outside from the output port.

By providing dummy intersections, the number of intersections is made equal for any light propagation path from the input port to the output port, so it is possible to obtain an output with the same intensity for light that passes through any path.

〔Example〕

Embodiments of the present invention will be described below with reference to FIG. 1 and FIGS. 5 to 8 of the accompanying drawings.

FIG. 1 is a functional circuit diagram showing the configuration of one embodiment. 2 ⁱ⁺¹ (i is a natural number) input port 1 (1
₍₁₎ , 1 ₍₂₎ , 1 ₍₃₎ , ...1 _(2i+1) ) are input optical input signals. Input port 1 has i-stage 1×2
Demultiplexing means 2 ₁₍₁₎ , 2 ₁₍₂₎ ,...2 _i(1) , 2 _i(2) ,...2 _i(22
An input branching tree 2 having a tree configuration consisting of _i) is connected, and the i-th stage 1×2 branching means 2 _i(1) , 2 _i(2) ,...2
From _{i (22i)} , 2 ⁽²ⁱ⁺¹⁾ types of branch signals are obtained. Then, in the i-th stage 1×2 demultiplexing means 2 _i ,
Furthermore, 2 ²ⁱ 2 × 2 optical switches 3 (3 ₍₁₎ , 3 ₍₂₎ ... 3 _(
22i) ) is connected as the i+1st stage of the tree, and forms a composite tree together with the input branch tree 2. Here, the two inputs of each of the ²²ⁱ 2x2 optical switches 3 have different input ports.
It is connected so that a branch signal branched from the terminal is input. Furthermore, two outputs are output from each of the 2×2 optical switches 3, and 2 ⁽²ⁱ⁺¹⁾ types of outputs are output from the 2×2 optical switches 3 as a whole. are connected to the inputs of 2 ²ⁱ 2×1 multiplexing means 4 ₁₍₁₎ , 4 ₁₍₂₎ , ...4 _1(22i) ,
sequentially connected to the inputs of the i-th 2×1 multiplexing main stages 4 _i(1) , 4 _i(2) ..., 4 _i(2i+1) via the i-stage multiplexing tree,
The output of the i-th multiplexing means 4 _i is connected to 2 ⁱ⁺¹ output ports 5 (5 ₍₁₎ , 5 ₍₂₎ , . . . 5 _{(2 i +1)} ). Connections between the input port 1 and the input branching tree 2 and the 2×2 optical switch 3 as well as between the output multiplexing tree 4 and the output port 5 are formed by a waveguide 6, and any of the input ports (e.g. 1
The optical input signal input to a) also passes through the input branching tree 2, the 2x2 optical switch 3, and the output multiplexing tree 4, and is then sent to all the output ports 5 (5 ₍₁₎ , 5 ₍₂₎ ,...
5 _(2i+1) ).

Furthermore, as indicated by the symbol DW, a dummy waveguide is provided that intersects the waveguide, forming a dummy intersection. These dummy intersections are provided so that the total number of intersections (the sum of the number of true intersections and the number of dummy intersections) is equal for any light propagation path from the input port to the output port. .

Next, the operation of the above embodiment will be explained. The optical input signals input to 2 ⁱ⁺¹ input ports 1 (1 ₍₁₎ , 1 ₍₂₎ ,...1 _(2i+1) ) are transferred to i-stage 1×2 demultiplexing means (2 _{i (1
)} , 2 _i(2) , ...2 _i(22i), the signal is branched into 2 ⁽²ⁱ⁺¹⁾ types of branch signals by ^the input branch tree 2 composed of 3 (3 ₍₁₎ , 3 ₍₂₎ ,…
3 _(22i) ) input. Each 2×2 optical switch 3 receives branch signals branched from different input ports 1 into two inputs, selects one of the two outputs, and outputs a switch output signal. 2×
1st stage 2×1 connected to the output of 2-optical switch 3
The multiplexing means (4 ₁₍₁₎ , 4 ₁₍₂₎ ,...4 _i(22i) ) multiplexes the input switch output signals and outputs them to the second stage 2×1 multiplexing means (4 _{2(1) )} , 4 ₂₍₂₎ ,...4 _2(22i-1) ), multiplexing is performed sequentially on the i-stage output multiplexing tree 4, and the i-th 2×1 multiplexing means (4 _{i( 1)} ,4 _i(2) ,...4
2 ^{i +1} types of optical outputs as outputs demultiplexed from _{i(2i+1) )} are supplied to the output port 5 .

Further, by providing the dummy intersections as described above, the total number of intersections is made equal for all light propagation paths, so that the light obtained at the output ports is approximately the same.

Next, an embodiment in which the present invention is applied to a 4×4 optical matrix switch will be described with reference to FIG. A
1 is a circuit diagram showing the configuration of this embodiment, and B is an explanatory diagram of the operation of a 2×2 optical switch constituting a redundant tree. The 4.times.4 optical matrix switch according to this embodiment corresponds to the case of i=1 in the ^2.sup.i+ 1.times.2 ⁱ⁺¹ optical matrix switch shown in FIG. Optical input signals input to four input ports 1a, 1b, 1c, and 1d are transferred to 1×2 demultiplexing means 2a, 2b, 2c, and 2d of an input branching tree consisting of only one stage.
through four 2x2 optical switches 3a, 3b, 3
It is connected to eight types of inputs: c, 3d. Eight types of outputs from the 2x2 optical switches 3a, 3b, 3c, and 3d are output from 2x1 multiplexing means 4a, 4b, 4c, and 4d of an output multiplexing tree consisting of only one stage.
4 output ports 5a, 5b, 5c,
5d. The four 2×2 optical switches 3a, 3b, 3c, and 3d constitute the second stage of the tree configuration for the input branching tree, and at the same time constitute the 2×1 tree for the output multiplexing. It also serves as a tree element in the preceding stage for the multiplexing means 4a, 4b, 4c, and 4d, and constitutes a so-called overlapping tree element. Then, the output of the input branch tree and 2 are made via the waveguide 6.
The connection between the input of the x2 optical switch and the connection between the 2x2 optical switch and the input of the output multiplexing tree is as follows. That is, the input of the 2x2 optical switch 3a is connected to one output of the 1x2 demultiplexing means 2a and one output of the 1x2 demultiplexing means 2b of the input demultiplexing tree, and the input of the 2x2 optical switch 3a is The input of the 2x2 optical switch 3c is connected to the other output of the 1x2 demultiplexer 2a and the other input of the 1x2 demultiplexer 2b, and the input of the 2x2 optical switch 3c is connected to one of the 1x2 demultiplexers 2c. Output and 1×2
It is connected to one output of the demultiplexing means 2a, and the input of the 2x2 optical switch 3d is connected to the other output of the 1x2 demultiplexing means 2c and the other output of the 1x2 demultiplexing means 2d. Further, the output of the 2×2 optical switch 3a is sent to one input of the 2×1 multiplexing means 4a and one input of the 2×1 multiplexing means 4b of the output multiplexing tree.
The output of the ×2 optical switch 3b is the 2×1 multiplexing means 4c.
The output of the 2x2 optical switch 3c is connected to one input of the 2x1 multiplexing means 4a and the other input of the 2x1 multiplexing means 4b. The output of the 2x2 optical switch 3d is
The other input of the 2×1 multiplexing means 4c and the other input of the 2×1 multiplexing means 4d are respectively connected.

Furthermore, as indicated by the symbol DW, a dummy waveguide is provided that intersects the waveguide, forming a dummy intersection. These dummy intersections are provided so that the total number of intersections (the sum of the number of true intersections and the number of dummy intersections) is equal for any point on the propagation path of light from the input port to the output port. It is something.

Next, the operation of the above embodiment will be explained. Optical input signals input from input ports 1a, 1b, 1c, 1d are transferred to 1×2 branching means 2a, 2b, 3c, 3.
2×2 branched by a branch tree consisting of d
It is input to optical switches 3a, 3b, 3c, and 3d.
At this time, 2×2 optical switches 3a, 3b, 3c,
Branch signals branched from different input ports 1a, 1b, 1c, and 1d are supplied to each of the two inputs of 3d. The switch output signals output from the 2×2 optical switches 3a, 3b, 3c, and 3d are multiplexed by an output multiplexing tree,
The signals are output as optical output signals to output ports 5a, 5b, 5c, and 5d. The operation of the 2.times.2 optical switch will now be described in more detail with reference to FIG. 5B.
The 2×2 optical switch 3 receives two inputs 31a and 31b and selects and outputs two outputs 32a and 32b, and is functionally equivalent to the tree shown on the right side of the figure. That is, this tree includes a 1x2 optical switch 33a that demultiplexes the input 31a, optical switches 34a and 34b connected to the tree, a 1x2 optical switch 33b that demultiplexes the input 31b, and these 1x2 optical switches 34a and 34b that demultiplex the input 31b.
It consists of optical switches 34a and 34b that receive and combine the outputs of optical switches 33a and 33b. The 2×2 optical switch on the left side of the figure is thus a demultiplexing means, which forms part of the demultiplexing tree, and a multiplexing means, which forms part of the demultiplexing tree. ing. This is why it is called a duplicate tree.

As a result, the 4×4 optical matrix switch of FIG.
The function of supplying the optical input signal input to 1d to all output ports 5a, 5b, 5c, and 5d via the 2×2 optical switch and output multiplexing tree that constitute the input branching tree and the redundant tree. It functions in the same way as a so-called non-blocking 4×4 optical matrix switch. The input branching tree and the output multiplexing tree perform the branching or multiplexing of information with almost no crosstalk, and the 2×2 optical switch 3a, which is one stage in the duplication tree,
In the case of 3b, 3c, and 3d, since the duplex tree is replaced with a single optical switch, crosstalk increases slightly, but the structure is simplified and miniaturization is facilitated.

In addition, as mentioned above, by providing dummy intersections using dummy waveguides, the total number of intersections is equal for all points on the propagation path of light, so the light obtained at the output port is approximately equal. be the same.

This point will be explained in detail below with reference to FIG.

Consider the signal light 41 passing through the waveguide 7c- _42a . When the signal light 42 also passes through the waveguide 7a- _42a , the signal lights 41 and 42 intersect at the intersection 43, causing crosstalk. Assuming that the amount of crosstalk to the waveguide 7a- _42a at the intersection 43 is 20 dB with respect to the amount of signal light 42,
Assume that the loss at ~44f is 2dB. signal light 4
Assuming that 1 and 42 had the same amount of light at the beginning,
When the signal light 41 passes through the intersection 43, it is reduced by 14 dB because it has already passed through the intersections 44a to 44f and 43. When the light 42 reaches the intersection 43, it has already passed through the intersections 46a to 46f, so it has decreased by 12 dB. Therefore, the amount of crosstalk is
The light intensity is 18 dB, which is an improvement of 12 dB compared to the case shown in FIG. 4, which is an example of a conventional configuration.

The above has described the crosstalk characteristics in the crossed waveguides, but the present invention also improves the crosstalk occurring in the optical switch section. The crosstalk that occurs in the optical switch section of this optical matrix switch is shown in Figure 5A, 3a, 3b, 3c, 3
The one that occurs in part d is the largest. These two
In a ×2 type optical switch, the maximum crosstalk occurs when light enters two input ports simultaneously.

The light entering from light switch 2a to 3b and the light entering from light switch 2b to 3b are
In Figure A, the former passes through the intersection once, so if there is no dummy waveguide 11b (as in Figure 4A), there will be a difference in the amount of light. Therefore, by applying the present invention, the same effect as at the intersection can be obtained. The paths that allow light to be simultaneously input to any two input ports of the optical switches 3a, 3b, 3c, and 3d are always adjacent to each other, and if there is no dummy waveguide, one intersection is always log ₂ n−
Only 1 more.

FIG. 7A shows the degree of improvement in the crosstalk amount/signal light amount with respect to the crosstalk occurring in the optical switch sections 3a to 3d. Figure 7B
indicates the degree of improvement in the worst case of crosstalk amount/signal light amount with respect to crosstalk occurring at the intersection.

FIG. 8 shows the S after improved by this invention.
The worst value of the ×R value is shown. Both the complete type and the simplified type have improved characteristics compared to the square lattice type.

Next, an example of an 8×8 optical matrix switch will be described. FIG. 9 is a circuit diagram showing the configuration of this embodiment, which corresponds to the case where i=2 in the optical matrix switch shown in FIG. The difference from the embodiment shown in FIG. 5A is that the input ports 1a, 1
h,...1d are composed of 8 ports, and the input branching tree is a 1×2 branching means consisting of two stages, with 2 _1a , 2
_1b ...2 _2a ...2 _2p formed by 32
2×2 optical switch 3a with 16 types of branch signals,
_3b , . . . 3p, and a 2×1 multiplexing means 4 _1a , 4 _{1b .}
. . 4 _2h , and the output signal is maintained at the output ports 5a, 5b, . . . , 5h consisting of eight ports.

The configuration shown in FIG. 9 forms unit matrices 7a, 7b, 7c, and 7d with the 4×4 optical matrix switch according to the configuration shown in FIG. 5A as one unit.
Arrange 4 units in parallel, input ports 1a, 1
b...2 groups of 1h with 4 ports each 1a to 1d, 1e
~1h, and the input signal can be understood as being allocated to the unit matrix 7 by the 1×2 demultiplexing means 2 _1a , 2 _1b . . . 2 _1h , which constitute the first stage of the input demultiplexing tree. can.

The structure of the optical matrix switch, which has been generalized through such unitization, is shown in the 10th
It is a diagram. 2 1 ( ¹ ₎ ,...1 _(2i
The input signal input to ₊₁₎ is divided into two parts by 2 ⁱ , and then divided into 1×2 demultiplexing means 2 ₍₁₎ ,...2 _(2i) or 2 _(2i+1) ...,
The two outputs outputted by 2 _(2i+1) are supplied to separate unit matrices 7a, 7b or 7c, 7d, respectively. Then, the output from the unit matrix is again 2×1 multiplexing means 4 ₍₁₎ ,...4 _(2i) or 4 _(2i+1) ,...4 _(
2i+1) and output as an output signal from 2i ⁺¹ output ports 5 ₍₁₎ ,...5 _(2i+1) .

Each of the 2 ⁱ × 2 ⁱ unit matrices 7a to 7d is
It has a configuration in which i is replaced with i+1 in FIG. However, when this is repeated until i=1, the unit matrix becomes 2×2 as shown in Figure 5B.
It's a light switch.

As mentioned above, by introducing the concept of a unit matrix, the 4 x 4 optical matrix switch shown in Figure 5A can also be generalized by considering a 2 x 2 optical switch as a unit matrix. This can be understood as the configuration shown in FIG.

In any of these embodiments, according to the present invention, a dummy waveguide DW is provided, dummy intersections are formed, and light passing through any path passes through the same number of intersections.

In the above embodiment, the 1×2 demultiplexing means is constituted by a 1×2 optical switch, and the 2×
Although it is possible to configure one multiplexing means with a 2×1 optical switch, it is also possible to configure only the 1×2 demultiplexing means with a 1×1 optical switch.
It is also possible to configure it with a two-light switch.

The present invention can also be applied to an optical matrix switch in which at least a portion of the waveguide connecting the optical switch, the demultiplexer, and the multiplexer is formed by a curve.

〔Effect of the invention〕

As described above, according to the present invention, an input signal inputted from an input port is inputted to an input branching tree consisting of a 1×2 branching means, and a switch is performed by a 2×2 optical switch that is connected to the input branching tree to form a redundant tree. The output signal is obtained and input to the output multiplexing tree consisting of 2x1 multiplexing means, and the output signal is obtained at the output port, so the optical switch means through which the information input to the input port passes is 21og. ₂ 2 ⁱ⁺¹ −1, and light loss is reduced. Furthermore, according to the present invention, an optical matrix switch can be configured with 3(i+1) ² /4 optical switches compared to a normal tree configuration without increasing crosstalk.
Furthermore, compared to an optical matrix switch consisting of a simple square lattice arrangement, an optical matrix switch can be configured with about 5/4 times as many optical switches, so it has excellent selection functions and less crosstalk. This is effective in providing a compact optical matrix switch.

Furthermore, dummy intersections are formed using dummy waveguides so that the number of intersections in the propagation path is the same no matter what route it takes, so the light intensity at the output port can be made approximately the same. .

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of one embodiment, FIGS. 2 to 4 are explanatory diagrams of the prior art, FIG. 5 is a circuit diagram showing the configuration of another embodiment, and FIG. 6 is an explanation of its operation. 7 and 8 are diagrams showing the amount of SxR improvement and the worst SxR, respectively, FIG. 9 is a circuit diagram showing the configuration of another embodiment, and FIG. 10 is a generalized diagram according to the present invention. FIG. 2 is a circuit diagram showing the configuration of an optical matrix switch. 1...Input port, 2...Input branch tree, 3
...2x2 optical switch, 4...output multiplexing tree,
5... Output port, DW... dummy waveguide.

Claims (1)

[Claims] An input port at 1 2 ⁱ⁺¹ (i is a natural number), and 2 ⁱ⁺¹
In the optical matrix switch, which has ^{2 output ports and selects the optical input signals supplied to the input ports in a matrix and outputs the optical input signals from the output ports as optical output signals, 1)} An input branching tree formed into a tree by i-stage 1×2 branching means that branches into different types of branching signals, and an input branching tree connected in series to the input branching tree to form one stage of an overlapping tree structure. 22i 2x2 optical switches which input two types of branched signals branched and supplied from different input ports, select one of the ^two outputs, and output a switch output signal; An output tree-configured by i-stage 2×1 multiplexing means, which inputs the switch output signal of the 2×2 optical switch and outputs the optical output signal to the 2 ⁱ⁺¹ output port. 1. An optical matrix switch characterized in that the number of intersections is made equal for any light propagation path from an input port to an output port by providing a dummy intersection.