RU2346316C1 - Optical signal switching unit - Google Patents

Abstract

FIELD: physics; optics.

SUBSTANCE: invention relates to optical data encoding, decoding and transmitting devices, in particular, to optical signal switching devices used in computer networks. Switching device comprises four logical units. Logical unit comprises inputs/outputs 1, 2, 3. The 1^st input/output of the 1^st - the 4^th logical units is input/output of the 1^st - the 4^th channels of the switching device, respectively. The 2^nd input/output of the 1^st logical unit is connected to the 2^nd input/output of the 3^rd logical unit. The 2^nd input/output of the 2^nd logical unit is connected to the 2^nd input/output of the 4^th logical unit. The 3^rd input/output of the 1^st logical unit is connected to the 1^st input/output of added 5^th logical unit. Its 2^nd input/output is connected to the 3^rd input/output of the 2^nd logical unit. The 3^rd input/output of the 4^th logical unit is connected to the 3^rd input/output of the 5^th logical unit. Its 4^th input/output is connected to the 3^rd input/output of the 3^rd logical unit.

EFFECT: simplified optical signal switching device and enhanced functional capabilities thereof.

2 cl, 5 dwg

Description

The present invention relates to devices for encoding, decoding and transmitting data represented by optical signals, in particular to optical signal switches used in computer networks.

Known wave filter switch optical signals [1], containing the first and second optical fibers, forming in a limited area fused and stretched twisted pair. The first input-output of the first optical fiber is the first multiplexed input-output of the switch. The second input-output of the first optical fiber is the first demultiplexed input-output of the switch. The first input-output of the second optical fiber is the second multiplexed input-output of the switch. The second input-output of the second optical fiber is the second demultiplexed input-output of the switch. The wave filter filter of optical signals [1] allows you to multiplex and demultiplex bi-directional optical signals with different wavelengths.

The disadvantage of the device [1] are limited functionality. In particular, it is impossible to switch optical signals between the first and second multiplexed or demultiplexed inputs / outputs. This does not allow using it as a central switching link when building a computer network with a star topology.

A known optical signal switch [2], containing four logical blocks, the logical block contains the first, second and third inputs / outputs, the first input-output of the first and fourth logical blocks is the input-output of the first and fourth channels of the switch. The logic unit is configured to transmit optical signals in certain directions. In particular, it can be configured to transmit signals in a computer network with a ring logical structure and star topology.

The disadvantages of the switch [2] are complexity and limited functionality.

The first drawback is the use of a matrix of mirrors with controlled transparency. Amplifiers are needed to compensate for signal attenuation in a chain of mirrors. Mirror transparency can be controlled manually when configuring the system or remotely. The latter option implies the availability of software-accessible controls (for example, based on a microprocessor with appropriate software); in any case, the switch must have the means to supply voltage to it, which leads to its additional complication and degrades performance.

The second disadvantage is that only one channel is used to transmit data in each direction.

The purpose of the invention is to simplify the switch and expand its functionality.

The goal is achieved by the fact that in the optical signal switch containing four logical blocks, the logical block contains the first, second and third inputs / outputs, the first input-output of the first - fourth logical unit is the input-output of the first and fourth channels of the switch, the second input-output the first logical block is connected to the second input-output of the third logical block, the second input-output of the second logical block is connected to the second input-output of the fourth logical block, the third input-output of the first logical block connected to the first input-output of the additionally introduced fifth logical unit, the second input-output of which is connected to the third input-output of the second logical unit, the third input-output of the fourth logical unit is connected to the third input-output of the fifth logical unit, the fourth input-output of which is connected with the third input-output of the third logical block, the first and fourth logical blocks contain wave filters of the first type, the fifth logical block contains a wave filter of the second type, multiplexed input one wave filter of the first type and the first multiplexed input-output of the wave filter of the second type are the first inputs and outputs of the corresponding logic blocks, the first and second demultiplexed inputs and outputs of the wave filter of the first and second types are the second and third inputs and outputs of the corresponding logic block, the second the multiplexed input-output of the filter of the second type is the fourth input-output of the fifth logical block.

In the proposed optical signal switcher, the wave filters of the first and second types operate with optical signals with wavelengths numbered in the form of a number λ1, λ2, λ3, ..., the wavelength increases uniformly with increasing number, the multiplexed input-output of the wave filter of the first type is transparent to optical signals with wavelengths with the numbers λ1, λ2, λ3, ..., the first demultiplexed input-output of the wave filter of the first type is transparent for optical signals with wavelengths with the numbers λ1, λ3, λ5, ... and opaque of natural signals with wavelengths with the numbers λ2, λ4, λ6, ..., the second demultiplexed input-output of the wave filter of the first type is transparent for optical signals with wavelengths with the numbers λ2, λ4, λ6, ... and opaque for optical signals with wavelengths with the numbers λ1, λ3, λ5, ..., the first and second multiplexed inputs and outputs of the wave filter of the second type are transparent for optical signals with wavelengths with numbers λ2, λ4, λ6, ..., the first demultiplexed input and output of the wave filter of the second type is transparent for optical signals with length mi waves with numbers λ2, λ6, λ10, ... coming from the first multiplexed input-output of this filter, and is opaque to optical signals with wavelengths with numbers λ4, λ8, λ12, ... coming from the first multiplexed input-output of this filter, the second demultiplexed input-output of the wave filter of the second type is transparent for optical signals with wavelengths λ4, λ8, λ12, ... coming from the first multiplexed input-output of this filter, and opaque for optical signals with wavelengths λ2, λ6, λ10, ... coming from the first multiplexed input-output of this filter, the first demultiplexed input-output of a wave filter of the second type is opaque to optical signals with wavelengths λ2, λ6, λ10, ... coming from the second multiplexed input-output of this filter, and is transparent for optical signals with wavelengths with numbers λ4, λ8, λ12, ... coming from the second multiplexed input-output of this filter, the second demultiplexed input-output of the wave filter of the second type is opaque to optical signals with wavelengths with numbers λ4, λ8, λ12, ... coming from the second multiplexed input-output of this filter, and is transparent for optical signals with wavelengths with numbers λ2, λ6, λ10, ... coming from the second multiplexed input-output this filter.

Figure 1, a presents a simplified sketch of the design of the known [1] wave filter; figure 1, b and c are variants of transparency diagrams of the wave filter of the first (F1) and second (F2) types; figure 2 and figure 3, a - examples of paths of the passage of optical signals through a wave filter of the first type; figure 3, b is an example of the inclusion of a filter of the first type in a data transmission system. Figure 4 presents the most common topologies for computer networks; figure 5 is a functional diagram of the proposed four-channel switch optical signals.

The wave filter 1 (figure 1, a) is designed to separate (sort) a group of signals by wavelengths. It is built on the basis of a specially twisted and fused with the simultaneous stretching of the melt optical fibers 2 and 3 [1]. Hereinafter, depending on the setting during its manufacture (filter of the first or second type), the filter is designated F1 or F2. In any case, the filter is symmetrical in the sense that the pairs of its terminals X-W, W-X, Y-Z and Z-Y are functionally equivalent.

Depending on the parameters of twisting, melting and stretching of the optical fibers during the manufacture of the filter, it acquires selective transparency with respect to the transmission of light signals of certain wavelengths. In other words, the filter can in some way sort the input stream of “multi-colored” infrared light signals arriving from outside in arbitrary combinations to pin X (to any of the four pins). The signals are assumed here to have wavelengths λ1, λ2, ..., λ16 uniformly distributed on the horizontal numerical axis of the graphs shown in FIGS. 1, b, c. Adjacent wavelengths are separated by gaps of 100 nm.

Graphs 4 and 5 (Fig. 1, b) represent one of the possible variants of the transparency diagrams of the channels X-Y and X-Z of the filter F1. Since the filter is symmetrical, the same graphs display the transparency diagrams of the W-Z and W-Y channels, as well as the two remaining channels obtained by mutually reverse substitution of the X, W symbols with the Y, Z symbols. Levels 0 and 100% correspond to the opaque and fully transparent channel states. The graphs for their simplification are represented by two antiphase sinusoids, although in reality their shape is more complex and depends on the filter manufacturing technology. From graph 4 it follows that the X-Y channel (as well as the W-Z channel) of the F1 filter is transparent for light with wavelengths λ1, λ3, λ5, ..., λ15 and opaque for light with wavelengths λ2, λ4, λ6, ..., λ16. If the channel is transparent, then light of the corresponding wavelengths can be transmitted through it in either or simultaneously in both directions. An opaque channel does not transmit light of the corresponding wavelengths in any direction.

Figure 5 shows that the X-Z channel (as well as the W-Y channel) of the F1 filter is transparent to light with wavelengths λ2, λ4, λ6, ..., λ16 and opaque to light with wavelengths λ1, λ3, λ5, ..., λ15.

Graphs 6 and 7 (Fig. 1, b) correspond to one of the possible variants of the transparency diagrams of the channels X-Y and X-Z (W-Z and W-Y) of the filter F2. They are represented by sinusoids with doubled periods compared to graphs 4 and 5. From graph 6 it follows that the channel XY of the filter F2 is transparent to light with wavelengths λ2, λ6, λ10, λ14 and opaque to light with wavelengths λ4, λ8, λ12, λ16. Graph 7 is out of phase with graph 6 and displays the transparency diagram of the X-Z channel of the F2 filter. The transparency of the X-Y and X-Z channels (W-Z and W-Y) of the F2 filter with respect to light signals with wavelengths λ1, λ3, λ5, ..., λ15 is undefined, but such signals do not arrive at this filter during its operation.

Examples 8-13 of the paths of the passage of optical signals through the wave filter F1 (figure 2, a-e) show the propagation of a group of light signals through the filter from left to right, from right to left and simultaneously in both directions. In these examples, one of the filter pins is not used.

In accordance with example 12 (Fig.2, d), the input-output X of the filter F1 is hereinafter referred to as multiplexed input-output, input-output Y - the first demultiplexed input-output, input-output Z - the second demultiplexed input-output of the filter. Similarly, the input-output X of the filter F2 is hereinafter referred to as the first multiplexed input-output, the input-output Y - the first demultiplexed input-output, the input-output Z - the second demultiplexed input-output. The input-output W of the filter F2 is called the second multiplexed input-output.

In examples 14-16 shown in figure 2, g, h and figure 3, and used all the conclusions of the filter F1.

Examples 14 and 15 show the possibility of using the filter F1 to interface unidirectional transmission lines of optical signals with bidirectional.

In example 14, the optical signal supplied to the input X on the left side contains 16 components with wavelengths λ1-λ16. The signal taken from the output of the filter W also contains 16 components with the same wavelengths λ * 1-λ * 16. The signs "*" indicate that the signals arrived at the inputs of the filter F1 on the right side. At the input-output Y, signals with wavelengths λ1, λ3, λ5, ..., λ15 propagate to the right, and signals with wavelengths λ * 2, λ * 4, λ * 6, ..., λ * 16 - to the left. At the input / output Z, signals with wavelengths λ2, λ4, λ6, ..., λ16 propagate to the right, and signals with wavelengths λ * 1, λ * 3, λ * 5, ..., λ * 15 - to the left.

Example 15 differs from example 14 in the directions of signal transmission through the terminals X and W of the filter F1.

In example 16 (Fig. 3, a), all lines connected to the filter F1 are bi-directional. On each line 16 pairs of oppositely directed optical signals are transmitted, each pair has the same wavelength. In essence, this scheme is not a fully connected switch capable of transmitting data in the directions: X → Y, X → Z, W → Y, W → Z, Y → X, Y → W, Z → X, Z → W. To select the direction of transmission (routing the information packet), the data source uses wavelengths with even or odd numbers. For example, an external source of the signal supplied to the input-output Z of the filter F1, wishing to transmit a message to the communication line connected to the input-outputs X or W, can use light pulses for this purpose with the corresponding wavelengths λ * 6 or λ * 15.

Direct data transfer in adjacent directions X → W, W → X, Y → Z, Z → Y is impossible. In the presence of an intermediary device 17 (FIG. 3, b), such transfers are feasible. For example, an external source of the signal supplied to the input-output Z of the filter F, wishing to transmit a message to the communication line 18 connected to the inputs / outputs Y, can use light pulses with a wavelength of λ * 8 for this. These pulses pass to input-output X and are received by device Q (17). According to preliminary "agreement" with this device, it immediately delivers the received pulses back to the input-output λ, but uses light with a wavelength of λ13 for this. Filter F1 transfers these pulses to input-output Y, as required.

The above examples (they can be extended to the F2 filter of the second type, taking into account its transparency diagram) show the previously mentioned limited capabilities of the filter [1] when it is used as a functionally complete switch of optical signals in a computer network.

Figure 4 presents the most common options for the topology of computer networks. The topology of the type of "common bus" (figure 4, a) is mainly used in local networks of early generations. Coaxial cables are commonly used as signal transmission medium. The use of fiber-optic communication lines within the framework of this topology is difficult, since it is necessary to install optical splitters to connect each node 19 to a common trunk 20. This is not technologically advanced, in addition, each splitter divides the energy of the signal arriving at it into two parts, so that the levels of the received signals depend from the relative position of the transmitter and receiver.

The topology of the star type with a common hub 21 (Fig. 4, b) implies the presence of radial connections between the hub and the nodes of the network 22. The concentrator summarizes all the optical signals entering it, distributes the total signal evenly between all channels, if possible, and simultaneously transmits it in the opposite directions. Some hubs work on the principle of distributing the input signal between all channels except for their own, which facilitates the detection of collisions while simultaneously addressing two or more nodes 22 to a common signal transmission medium.

The main disadvantage of this structure is that the input signal power is divided by the number of channels reaching one hundred or more. To restore the levels of the output signals, active concentrators are used, which are able to enhance the power of the light fluxes emitted by them in all directions. This complicates the structure of the hub and requires a power source.

In a network with a ring topology (FIG. 4, c), the nodes 23 are connected in a series closed circuit. The disadvantages inherent in the previously discussed networks (figure 4, a, b), in this case are absent. Each node suspends the distribution of information packets addressed to it and transmits “foreign” packets to the next node.

In the event of a failure of a node, the main direction of packet transmission, having reached the node closest to it, can be reversed, so that all nodes that are still operational are accessible. In order to preserve the possibility of bi-directional data transmission in a ring in case of failure of one of the nodes, this node is automatically or manually excluded from operation, and optical communication lines broken by such a failure are connected directly. In this case, the connecting element introduces losses in the transmission of the signal, in addition, the length of the newly created communication line becomes equal to the sum of the lengths of communication lines that previously connected the failed node to the neighboring ones.

This disadvantage is absent in the network with combined topology (figure 4, g). Outwardly, it resembles a previously considered network with a star topology (Fig. 4, b), but instead of a hub 21, it uses a switch 24 connected to nodes 25. Unlike a hub, switch 24 is capable of combining optical fibers in a certain way connecting it with the nodes 25. For example, inside the switch, you can create connections in which the network has a ring logical structure similar to that shown in figure 4, c. Arrows 26 in FIG. 4, d correspond to packet transmission routes between nodes 25. As follows from the above diagram, packet transmission between nodes 25 occurs essentially along arrows 27, as in a network with a ring topology.

Isolation and bypass of one or more faulty nodes 25 is carried out by the corresponding adjustment of the internal circuits of the switch 24 and does not affect the network nodes and communication lines.

The switch 28 [2] (Fig. 4, e) contains logical blocks 29, the logical block contains the first 30, second 31 and third 32 inputs / outputs, the first input-output 30 of the logical unit 29 is the input-output of the corresponding channel of the switch. The inputs / outputs 30 of the logical blocks 29 are connected to the nodes 33 of the network.

Logic blocks 29 can be configured to transmit signals between nodes 33 in a ring pattern, as was shown in figure 4, d. Other settings are also possible.

The proposed switch, shown in figure 5, contains four logical blocks 34-37, the logical block contains the first 38, second 39 and third 40 inputs / outputs, the first input-output 38 of the first and fourth logical blocks 34-37 is the input-output of the first - the fourth channel 41-44 of the switch, the second input-output 39 of the first logical block 34 is connected to the second input-output 39 of the third logical block 36, the second input-output 39 of the second logical block 35 is connected to the second input-output 39 of the fourth logical block 37, third input-output 40 of the first log unit 34 is connected to the first input-output 45 of the additionally introduced fifth logical block 46, the second input-output 47 of which is connected to the third input-output 40 of the second logical block 35, the third input-output 40 of the fourth logical block 37 is connected to the third input-output 48 of the fifth logical block 46, the fourth input-output 49 of which is connected to the third input-output 40 of the third logical block 36, the first and fourth logical blocks 34-37 contain wave filters F1 of the first type (Fig. 1, a, b), the fifth logical block 46 contains a wave the filter F2 of the second type (Fig. 1, a, c), the multiplexed input-output X of the wave filter F1 of the first type and the first multiplexed input-output X of the wave filter F2 of the second type are the first inputs-outputs 38, 45 of the corresponding logic blocks, the first Y and the second Z, the demultiplexed inputs and outputs of the wave filter of the first F1 and second type F2 are respectively the second 39, 47 and third 40, 48 inputs and outputs of the corresponding logic block, the second multiplexed input-output W of the filter of the second type F2 is the fourth input m-output 49 of the fifth logical block 46.

When the switch is switched on to the computer network, its nodes are connected to the inputs and outputs 41-44 of the first and fourth channels. For convenience of presentation in figure 5, the channels are indicated by the letters A, B, C and D.

To exchange data between network nodes, optical signals with wavelengths λ1-λ16 uniformly distributed on the horizontal numerical axes of the diagrams shown in Fig. 1 are used. The switch provides a complete graph of bidirectional connections:

А↔В, А↔С, А↔D, В↔С, В↔D, С↔D.

To indicate the directions of signal transmission through the switch, shown in figure 5, the following notation. In a record of the form “λ1 ^A, ” the superscript indicates the signal source (in this example, the device connected to channel A) with a wavelength of λ1. Thus, according to figure 5:

λ2 ^A , λ6 ^A , λ10 ^A , λ14 ^A - wavelengths for data transmission from channel A to channel B;

λ2 ^B , λ6 ^B , λ10 ^B , λ14 ^B - wavelengths for data transmission from channel B to channel A;

λ1 ^A , λ3 ^A , λ5 ^A , ..., λ15 ^A - wavelengths for data transmission from channel A to channel C;

λ1 ^C , λ3 ^C , λ5 ^C , ..., λ15 ^C - wavelengths for data transmission from channel C to channel A;

λ4 ^A , λ8 ^A , λ12 ^A , λ16 ^A - wavelengths for data transmission from channel A to channel D;

λ4 ^D , λ8 ^D , λ12 ^D , λ16 ^D - wavelengths for data transmission from channel D to channel A;

λ4 ^B , λ8 ^B , λ12 ^B , λ16 ^B - wavelengths for data transmission from channel B to channel C;

λ4 ^C , λ8 ^C , λ12 ^C , λ16 ^C - wavelengths for data transmission from channel C to channel B;

λ1 ^B , λ3 ^B , λ5 ^B , ..., λ15 ^B - wavelengths for data transmission from channel B to channel D;

λ1 ^D , λ3 ^D , λ5 ^D , ..., λ15 ^D - wavelengths for data transmission from channel D to channel B;

λ2 ^C , λ6 ^C , λ10 ^C , λ14 ^C - wavelengths for data transmission from channel C to channel D;

λ2 ^D , λ6 ^D , λ10 ^D , λ14 ^B - wavelengths for data transmission from channel D to channel C.

In this case, each network node can simultaneously and bilaterally exchange data with any nodes using four or eight wavelengths in each direction of transmission and reception.

The application of the proposed optical signal switch allows simplifying the construction of networks with a fully connected graph of connections between its nodes or with a logical structure of the ring type and star topology. Due to the possibility of simultaneous communication of each channel with each, the logical isolation of faulty network nodes is implemented. The switch operates without a power source. The route of the data packet transmitted by the network node is specified at the physical (and not at the network) level by selecting the wavelength of the linear signal.

Information sources

1. US patent No. 5.809.190 (Fig. 5).

2. US patent No. 6.134.357 (Fig.4) (prototype).

Claims (2)

1. The optical signal switch containing four logical blocks, the logical block contains the first, second and third inputs / outputs, the first input-output of the first - fourth logical unit is the input-output of the first and fourth channels of the switch, characterized in that the second input-output the first logical block is connected to the second input-output of the third logical block, the second input-output of the second logical block is connected to the second input-output of the fourth logical block, the third input-output of the first logical block is connected inen with the first input-output of the additionally introduced fifth logical block, the second input-output of which is connected to the third input-output of the second logical block, the third input-output of the fourth logical block is connected to the third input-output of the fifth logical block, the fourth input-output of which is connected with the third input-output of the third logical block, the first and fourth logical blocks contain wave filters of the first type, the fifth logical block contains a wave filter of the second type, multiplexed input-output in the first filter of the first type and the first multiplexed input-output of the wave filter of the second type are the first inputs and outputs of the corresponding logic blocks, the first and second demultiplexed inputs and outputs of the wave filter of the first and second types are the second and third inputs and outputs of the corresponding logic block, the second is multiplexed the input-output of the filter of the second type is the fourth input-output of the fifth logical block. 2. The optical signal switch according to claim 1, characterized in that the wave filters of the first and second types operate with optical signals with wavelengths numbered in the form of a series of λ1, λ2, λ3, ..., the wavelength increases uniformly as its number increases, multiplexed the input-output of the wave filter of the first type is transparent for optical signals with wavelengths λ1, λ2, λ3, ..., the first demultiplexed input-output of the wave filter of the first type is transparent for optical signals with wavelengths λ1, λ3, λ5, ... and not about Designed for optical signals with wavelengths λ2, λ4, λ6, ..., the second demultiplexed input-output of the wave filter of the first type is transparent for optical signals with wavelengths λ2, λ4, λ6, ... and opaque for optical signals with wavelengths with numbers λ1, λ3, λ5, ..., the first and second multiplexed inputs and outputs of the wave filter of the second type are transparent for optical signals with wavelengths with numbers λ2, λ4, λ6, ..., the first demultiplexed input and output of the wave filter of the second type is transparent for optical whitefish waves with wavelengths λ2, λ6, λ10, ... coming from the first multiplexed input-output of this filter, and is opaque to optical signals with wavelengths with numbers λ4, λ8, λ12, ... coming from the first multiplexed input-output of this filter, the second demultiplexed input-output of the wave filter of the second type is transparent for optical signals with wavelengths λ4, λ8, λ12, ... coming from the first multiplexed input-output of this filter, and is opaque for optical signals with wavelengths with frame λ2, λ6, λ10, ... coming from the first multiplexed input-output of this filter, the first demultiplexed input-output of the wave filter of the second type is opaque for optical signals with wavelengths with numbers λ2, λ6, λ10, ... coming from the second multiplexed input -output of this filter, and is transparent for optical signals with wavelengths with numbers λ4, λ8, λ12, ... coming from the second multiplexed input-output of this filter, the second demultiplexed input-output of the wave filter of the second type is opaque It is transparent for optical signals with wavelengths with numbers λ4, λ8, λ12, ... coming from the second multiplexed input-output of this filter, and is transparent for optical signals with wavelengths with numbers λ2, λ6, λ10, ... coming from the second multiplexed input -output of this filter.

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