JPS63259519A - Optical matrix switch - Google Patents

Abstract

PURPOSE:To reduce crosstalk, and to miniaturize the titled switch by inputting an input signal inputted from an input port, to an input demultiplexing tree consisting of a 1X2 demultiplexing means, obtaining a switch output signal by a 2X2 optical switch which is connected to said tree and constitutes an overlap tree, and inputting it to an output multiplexing tree consisting of a 2X1 multiplexing means. CONSTITUTION:An optical input signal inputted to 2<i+1> pieces of input ports 1 [1(1), 1(2),...(2<i+1>)] is allowed to branch to 2<(2i+1)> kinds of branching signals by an input demultiplexing tree 2 constituted of 1X2 demultiplexing means [2i(1), 2i(2),...2i(2<2i>)] of (i) stages, and inputted to inputs of 2<2i> pieces of 2X2 optical switches 3 [3(1), 3(2),...3(2<2i>)]. The respective 2X2 optical switches 3 input a branching signal which is allowed to branch from each different input port 1, to two inputs, select one of two outputs and output a switch output signal. Subsequently, multiplexing is executed successively with regard to an output multiplexing tree of (i) stages, and 2<i+1> kinds of optical outputs being outputs demultiplexed from the i-th 2X1 multiplexing means [4i(1), 4i(2),...4i(2<i+1>)] are supplied to an output port 5.

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 is a story about an optical matrix switch that outputs as 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 configuration of an optical matrix switch using such a waveguide type optical switch. 1iNb
On the substrate 9 having the electro-optic effect of 03, sixteen 2×2 optical switches 91 are arranged in a square lattice of 4 rows and 4 columns. One input and output of each of the 2×2 optical switches 91 constituting a row are connected in series via a waveguide 93 to the four input ports 1a, 1b, 1c, and 1d. The output of the 2×2 optical switch 91 is connected to four output ports 2a, 2b, 2G, and 2d. In addition, among the outputs of each 2×2 optical switch 91, the other output that does not form a row is connected to the waveguide 93 to the other input that does not form a row of the adjacent 2×2 optical switch 91 in the subsequent column.
The 2×2 optical switches 91 are connected to each other diagonally. According to the above-mentioned conventional technology, the information input from any of the input ports 1a, 1b, lc, and Id is transmitted to a 2×2 matrix arranged at the intersection of the matrix.
The optical switch 91 switches the direction of the outgoing lines into a so-called direct state or a crossed state. Compared to the most basic optical switch, which is constructed by arranging optical switches in rows and columns in a square lattice and orthogonally connecting each optical switch, although it is composed of the same number of optical switches, The means of optical switch passing through any combination of input ports and output ports is always constant,
Furthermore, since it requires only 1/2i+1 of the worst case scenario in a basic optical matrix switch, it has the characteristic of reducing optical loss and cross 1-1.

However, even with the above-mentioned conventional technology, the information input from the input port 1b as shown by the solid line arrow in FIG. However, the 2×2 optical switch 91 has a disadvantage in that crosstalk occurs.

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 substrate 9 there are input ports 1a, 1b, 1c.

16, which becomes a square grid array with 4 rows and 4 columns connected to 1d.
2X2 optical switch 94, output ports 2a, 2b,
A similar 2×2 optical switch 95 connected to 2G and 2d is arranged. The 2X2 optical switch 9 is located at each grid intersection on the input port side and the output port side.
4.95, the waveguide 93 is arranged so that each row on the input port side is positioned one row on the output port side for each column on the input port side.
are interconnected by.

According to this, since there is no case where different information is input to one 2X2 optical switch, the information input to the input port can be matrix-selected and output to the output port without causing almost any crosstalk. Can be done.

[Problems that the invention seeks to solve]

However, with the above 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, 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 input port side. For this reason, twice as many optical switches are required as compared to an optical matrix switch that uses a simple square lattice arrangement, so the overall size of the optical matrix switch becomes larger. This also increases the number of optical switches that can be used.

Another problem was that light loss could not be reduced.

Therefore, the present invention can be configured with the same number of optical switches as in an optical matrix switch consisting of a simple square lattice arrangement, has fewer stages of optical switches from an input port to an output port, and can be formed compactly. Another object of the present invention is to provide an optical matrix switch with crosstalk characteristics.

[Means for solving problems]

In order to achieve the above object, the optical matrix switch according to the present invention has an i-stage IX2 demultiplexer that branches an optical input signal input from 2i+l (H is a natural number) input ports into 2 (2i+1) branch signals. an input branching tree having a tree configuration consisting of means; and two types of branching signals that are connected in series to the input branching tree to form one stage of a redundant tree configuration, and are branched and supplied from different input ports. 22i 2x2 optical switches that select one of two outputs and output a switch output signal;
Input the switch output signal of ×2 optical switch and
2× of i stage that outputs the optical output signal to the output port of i+1
The apparatus is characterized in that it includes an output multiplexing tree configured as a tree consisting of one multiplexing means.

[For production]

According to the present invention, since the optical matrix switch is configured as described above, the optical input signals supplied to the 2i+i input ports are divided into two by the i-stage 1×2 demultiplexing means constituting the input demultiplexing tree. Branched into (2i+1) branch signals,
One of the branched signals from the different input ports supplied to two of the 22i 2×2 optical switches forming one stage of a single-multiple tree in phase with the input branched tree is selected to produce two outputs. The signal is output as a switch output signal to one of the switch output signals, and is branched into 2i+1 output signals by i-stage 2X1 multiplexing means constituting an output multiplexing tree into which the switch output signal is input, and then supplied to the outside from the output port. It acts on

〔Example〕

Hereinafter, the present invention will be described in detail with reference to FIG. 1 and FIGS. 4 to 7 of the accompanying drawings.

FIG. 1 is a functional circuit diagram showing the configuration of one embodiment. 2!
+1 (i is a natural number) input port 1 (1 (1)
1(2)・1(3)・−1(2i+1))” are input with optical input signals.Input port 1 has 1 of stage i.
×2 demultiplexing means 2i(1)=2i(2)=...2i(
1), 2i (2), ... 2i (22) input branch tree 2 is connected, and the first stage 3 (2
2i) ) is connected as the i+" first stage of the tree, forming a composite tree together with the input branching tree 2. Here, the two-man power of each of the 22i 2x2 optical switches 3 is as follows: It is connected so that branch signals branched from different input ports 1 are input.Furthermore, 2X
Two outputs are output from each of the two optical switches 3, and there are 2 (2++1) types of outputs in the 2X2 optical switch 3 as a whole.
2i 2×1 multiplexing means 41(1)=41(2)=・
...41 (connected to 22 inputs, sequentially connected to the first stage 2X1 multiplexing means 41 (1), 41 via the first stage multiplexing tree
(2).

5 (5(1) -5(2) =...5(2i+1)
)It is connected to the. The connections between the input port 1 and the input branching tree 2 and the 2X2 optical switch 3 as well as the output multiplexing tree 4 and the output port 5 are formed by a waveguide 6. The optical input signal to be output also passes through the input branching tree 2, the 2X2 optical switch 3, and the output multiplexing tree 4, and then passes through all the output ports 5 (5(1)).

5(2), . . . 5(z!"1)).

Next, the operation of the above embodiment will be explained. Input port 1 of 2i+i (1(1), 1(2),...1(2i
The optical input signal input to the optical input signal (2i +1) types of branch signals, and 22i 2×2 optical switches 3 (3(1) = 3(2) =・
...3 (22i)) input. 2x each
The two-optical switch 3 inputs branch signals branched from two different input ports 1 car, selects one of the two outputs, and outputs a switch output signal.

The first stage 2X1 multiplexing means connected to the output of the 2X2 optical switch 3 - (41 (1) - 41 (2) - 41 (22
) is the second stage 2X1 multiplexing means (442(2)) which multiplexes the input switch output signals.

2(1)...42(22t-1)), and multiplexing is performed sequentially for the i-stage output multiplexing tree 4, and the first stage 2×1
Supply to Kaporto 5.

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) 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 forming an overlapping tree. The 4×4 optical matrix switch according to this embodiment is a 2 i+I X2 i+1 optical matrix switch illustrated in FIG.
This corresponds to the case where =1. 4 input ports 1a.

The optical input signals inputted to 1b, 1c, and 1d are transferred to 1×2 demultiplexing means 2a, 2 of the input branch tree consisting of only one stage.
"Four 2x2 optical switches 3a via b, 2c, 2d
, 3b, 3c, and 3d.

And 8 of 2X2 optical switches 3a, 3b, 3c, 3d
The various outputs are connected to four output ports 5a, 5b, 5c, and 5d via 2×1 multiplexing means 4a, 4b, 4c, and 4d of an output multiplexing tree consisting of only one stage. . And four 2×2 optical switches 3a, 3b.

3c and 3d are tree 2×1 multiplexing means 4a, 4b, and 4c that constitute the second stage of the tree configuration for the input branching tree, and at the same time, for the output multiplexing.

It also serves as a preceding tree element for 4d, and constitutes an element of a so-called overlapping tree. The connection between the output of the input branch tree and the input of the 2X2 optical switch and the connection between the 2X2 optical switch and the input of the output white wave tree, which are made via the waveguide 6, are 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 2x2 optical switch 3b
The input of the 2x2 optical switch 3G 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 3G is connected to one output of the 1x2 demultiplexer 2C. 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.
It is connected to the other output of the two-way splitting means 2d. Also,
The output of the 2×2 optical switch 3a is 2× of the output multiplexing tree.
The output of the 2x2 optical switch 3b is connected to one input of the 2x1 multiplexing means 4a and one input of the 2x1 multiplexing means 4b, and the output of the 2x2 optical switch 3b is connected to one input of the 2x1 multiplexing means 4C and one input of the 2x1 multiplexing means 4d. The output of the 2x2 optical switch 3C is input to the other input of the 2x1 multiplexing means 4a, and the output of the 2x2 optical switch 3d is input to the other input of the 2x1 multiplexing means 4b. Multiplexing means 4
C and the other input of the 2×1 multiplexing means 4d,
each connected.

Next, the operation of the above embodiment will be explained. input boat 1a,
The optical input signal input from 1b, ice 1t:j is
It is branched by a branching tree consisting of 1X2 branching means 2a, 2b, 3G, and 3d to form 2X2 optical switches 3a, 3b.
, 3c, and 3d. At this time, 2X2 optical switches 3a, 3b, 3c.

3d each has a different input port 1a
, 'lb, 1c, and 1d are supplied with branch signals. And 2X2 optical switches 3a, 3b, 3c
, 3d are multiplexed by the output multiplexing tree, and the output ports 5a, 5b, 5G,
5d as an optical output signal. Here, the operation of the 2×2 optical switch will be explained in more detail with reference to FIG. 4(B).゛The 2×2 optical switch 3 is powered by two people 31a, 31
b is input to select and output two outputs 32a and 32b, and is functionally equivalent to the duplicate tree shown on the right side of the figure. That is, this redundant tree includes a 1X2 optical switch 33a that demultiplexes the input 31a, optical switches 34a and 34b connected to the tree, an 'IX2 optical switch 33b that demultiplexes the input 31b, and these 1X2 optical switches 33a and 33b.
It consists of optical switches 34a and 34b that receive and combine the outputs of. The 2X2 optical switch on the left side of the figure is thus a demultiplexing means, which constitutes a part of the demultiplexing tree, and a multiplexing means, which constitutes a part of the demultiplexing tree. . This is why it is called a duplicate tree.

As a result, the 4X4 optical matrix switch of FIG. 4(A) has either input port 1a or 1b.

The optical input signal input to 1C2id is also transmitted to all output ports 5a and 5b via the 2x2 optical switch and output multiplexing tree that constitute the input branching tree and the overlapping tree.
, 5c, and 5d, and functions in the same manner as a so-called non-blocking type 4X4 optical matrix switch. The 2X2 optical switch 3a performs demultiplexing or multiplexing of information with almost no crosstalk in the input demultiplexing tree and the output multiplexing tree, and serves as one stage in the duplicating tree.

In the case of 3b, 3G, 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.

The circuit configuration shown in FIG. 8 is equivalent to that in FIG. 4 (A>. That is, the output multiplexing means 4a', 4b'
, 4G' and 4d' are respectively shown in FIG.
Corresponding to 4C14b and 4d, output port 5a',
5b', 5c' and 5d' are respectively output port 5
It corresponds to a, 5c, 5b, and 5d.

Next, an example of an 8×8 optical matrix switch will be described.

FIG. 5 is a circuit diagram showing the configuration of the embodiment, which corresponds to the case where i=2i+1 in the optical matrix switch shown in FIG. The difference from the embodiment shown in FIG. 4 is as follows.
Input ports la, 1b.

...1d is composed of 8 ports, and the input branch tree is 2
2ia, 2ib... in the 1X2 demultiplexing means consisting of stages
22a...22p, resulting in 32
A 2X2 optical switch 3a with 16 types of branch signals.

3b, . . . 3p, and 2X1 multiplexing means 41a, 41b, .

42, . . . , 42h, and the output signal is connected to output ports 5a, 5b, .

The configuration shown in FIG. 5 has a unit matrix 7a with the 4×4 optical matrix switch according to the configuration shown in FIG. 4 as one unit.
, 7b, 7c, and 7d are arranged in four units in parallel, and the input ports 1a, 1b...1h are divided into two groups of 4 ports 1a to 1d, Ie to 1h, and the input branch tree is 1X2 demultiplexing means 2i0, 2ib configuring the first stage...
- By 2ih, the input signal can be understood as having been allocated to each unit matrix 7.

The configuration of an optical matrix switch that was generalized through such unitization was shown in Figure 6, and then
1×2 demultiplexing means 2(1)--2(2') or 2(2
'+i), 2(2i+1)' The two outputs output from - are respectively supplied to separate unit matrices 7a, 7b or 7G, 7d.Then, the outputs from the unit matrices are again output from the 2X1 multiplexer. be done.

2! Each of the x2i unit matrices 7a to 7d has a configuration in which i is replaced with 1+1 in FIG.

However, when this is repeated and 1=1, the unit matrix is a 2×2 optical switch shown in FIG. 4(B).

As mentioned above, by introducing the concept of a unit matrix, the 4X4 optical matrix switch shown in FIG. This can be understood as the configuration shown in FIG.

The circuit configuration shown in FIG. 9 is equivalent to that shown in FIG. Similar to the relationship between Figure 8 and Figure 4 (A>), it can be seen that the white wave means on the output side and the arrangement of the output port are simply changed. Since this affects the dimensions per stage of the means, etc., it is necessary to take this into consideration when choosing which circuit configuration to adopt.

Note that in the above embodiment, the 1×2 demultiplexing means is constituted by a 1×2 optical switch, and the 2×1 multiplexing means is constituted by 2×2 optical switches.
Although it is also possible to configure it with an X1 optical switch,
It is also possible to configure only the IX2 demultiplexing means with a 1×2 optical switch.

In particular, when the demultiplexing means is configured with a passive demultiplexing means, the two-man power of the 2×2 optical switch 3 can be used as shown in FIG.
0N10FF switch 35a.

35b can be provided to configure an optical matrix switch. According to this, if the input branching tree and the output multiplexing tree are configured by passive branching and multiplexing, the optical matrix switch will have two stages of optical switches, so the overall configuration of the optical matrix switch will be can be miniaturized, and particularly when the number of input ports is eight or more, the size can be significantly miniaturized.

In addition, in FIG. 4(A), FIG. 5, FIG. 6, FIG. 8, and FIG. 9, it is also possible to adopt a matrix configuration in which the input ports and output ports are exchanged.

FIGS. 10(A) to 10(C) show still another embodiment of the present invention. In these embodiments, the waveguide connections themselves are the same as those in the embodiments shown in FIGS. 8, 4 (A>, and 9), respectively. A point where at least a part of the waveguides to be connected is formed by a curved line.In other words, the direction of the straight line connecting the corresponding input ports and output ports of the same number is the longitudinal direction, and the direction perpendicular to this is the longitudinal direction. When referred to as the lateral direction, at least a portion, for example, the entire waveguide 61 connecting the optical switch, the demultiplexer, and the multiplexer located at positions shifted in the lateral direction is formed by a curved line.The curved line is an example shown in the drawing. consists of a combination of circular arcs.Using a curved waveguide allows the longitudinal dimension of the optical matrix to be reduced.

This point will be explained below with reference to FIG. The figure shows two curved waveguides W1 and W2 that intersect with each other, and the curved portions each consist of a combination of circular arcs centered on points R1 to R4.

As shown in the figure, it is assumed that each element E1 to E4 such as an optical switch, a demultiplexer, a multiplexer, etc. are aligned in the longitudinal direction and the lateral direction, and the distance between the elements in the lateral direction is Y, and the longitudinal direction is In the case of a curved waveguide, the distance between elements in the direction is
The case of a single straight waveguide is designated as X'. The dimensions x and x' are constrained by the branch angle 2α of the branch and the intersection angle 2 of the intersection.
θ. That is, the branching angle 2α is usually about 2° or less, and even if a special one is used, it can only be increased to about 4°. On the other hand, the crossing angle 2θ is 4 to avoid crosstalk.
It is necessary to set the angle to about 7° or more.

In the case of a straight waveguide and the case of a curved waveguide, the branching angle 2α
are the same, the curved waveguide can have a larger crossing angle 2θ than the straight waveguide, and can shorten the distance X between the elements. In addition, in the case of a straight waveguide, the crossing angle and the branching angle are the same, and the required crossing angle (4~
7°) requires a special optical switch, but in the case of a curved waveguide, the branching angle can be made smaller than the crossing angle, so a special optical switch is not required.

The effect of using such a curved waveguide becomes more significant as the distance Y between the elements to be connected to each other increases. This will be explained below with reference to FIG. For simplicity, let the branching angle 2α be O -0 Also, 2θ, X,
Y indicates the same thing as in FIG. 11, and R indicates the radius of curvature of the curved waveguide.

Considering the branch point E1 as the origin of the xy coordinates, from the circle equation (X/2>2+((Y/2>-R)2=R2...
・(1) Therefore, X=2(YR-Y-74>172 ・・・・・・(2
) If Y is sufficiently small compared to R, then X=(4YR) 1/2 -------(3)
As can be seen from equation (3), as Y increases,
It only increases in proportion to the 1/2> power. On the other hand, in the case of a straight waveguide, X increases in proportion to Y.

Therefore, the larger the distance Y between elements to be connected to each other, the more significant the effect of using a curved waveguide (x is relatively small).

As the number of ports increases, it becomes necessary to connect elements with greater lateral separation, and a larger value of Y exists. It can be said that the effect is large.

Examples of trial calculation results for the total length of an optical matrix switch are shown in FIGS. 13 and 14. Figure 13 is a plot of the number of boats. = Q), the same figure (B) is a complete type, that is, the case where all the demultiplexing means and the multiplexing means are composed of optical switches (element length, us = 2>, the same figure (C) is a simple type,
In other words, all of either the demultiplexing means or the multiplexing means is composed of optical switches, the length of the element pS=2), and all of the usage is composed of passive means (the length of the element fJ5=Q
) indicates the case. The radius of curvature R=10.20.30 m is shown. The same figure (if A>, R=10.20.3
In each case of 0 m, the inter-element pressure of a 2×2 optical switch!
ttyu (Y=force direction and Xu (X direction) are respectively as follows.

At R=10m, yu=o, o4#, XU=1.2#
At R=20m, Y U =0.074 Irn, X
u = 2.4 # At R = 30m, Y u = 0.1
12 rrm, XU=3.6 #It is assumed that the intersection angle 2θ is 7°.

FIG. 14 is a plot of the total length of a 16×16 type optical matrix switch corresponding to the radius of curvature. The figure (A) shows the complete type, and the figure (B) shows the simplified type.

〔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 1X2 branching means, and a switch output signal is transmitted by a 2×2 optical switch connected thereto to form a redundant tree. Since the information input to the input port passes through i+1, the number of stages of optical switches is 2ioq22- 1, and light loss is reduced. Further, 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. Compared to an optical matrix switch consisting of
Since the optical matrix switch can be configured with about 4 times the number of optical switches, it is possible to provide an optical matrix switch that has an excellent selection function, has little crosstalk, and is small in size.

Furthermore, if a curved waveguide is used, the length of the optical matrix can be further reduced.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing the configuration of one embodiment, Figures 2 and 3.
4 is a circuit diagram showing the configuration of another embodiment and its operation explanation diagram. FIG. FIG. 7 is a circuit diagram showing a configuration of a generalized optical matrix switch according to the invention, FIG. 7 is a circuit diagram showing another configuration of an optical switch applicable to an embodiment of the invention, and FIGS. Figures 11 and 12 are diagrams showing changes in dimensions when a curved waveguide is used, and Figures 13 and 14 are diagrams showing trial calculations of the total length of the optical matrix switch. 1...Input port, 2...Input branch tree, 3...
・2×2 optical switch, 4... Output multiplexing tree, 5...
・Output port. 2''' Circuit diagram of one implementation part 1 1st sheep 3 Masked caboto (, 4) (, a) Circuit diagram of the implementation of the grip 4th figure 5th day tea 6th day (β mouth rumor ( ) A death θ Bunmi ke 10th death map page 10 Rf6
'R4 curve 45 branch and liL Oka leading 3L 1st if episode! Figure 2 Boat Minute Number of Boats n Port Beast n Boat Beast ℃9 Matrix Suitsuna
IBI*IPRCyt creation curve prison R (m7ff41
Curvature hand shoe matori 7 tin tuna or full length I4 figure

Claims (1)

[Claims] An input port at 2^i^+^1 (i is a natural number), and 2
^i^+^In an optical matrix switch that has one output port, selects the optical input signal supplied to the input port in a matrix, and outputs the optical input signal from the output port as an optical output signal, the optical input signal is input. an input branch tree configured by i-stage 1×2 branching means, which branches into 2^(^2^i^+^1^) types of branch signals; and the input branch tree. are connected in series to form one stage of a redundant tree configuration, and input two types of branched signals that are branched and supplied from different input ports, and select one of the two outputs to output a switch output signal. Output 2^2^
i 2x2 optical switch and i stage 2x which inputs the switch output signal of the 2x2 optical switch and outputs the optical output signal to the 2^i^+^1 output port. 1. An optical matrix switch comprising: an output multiplexing tree configured by a single multiplexing means.