RU2346307C1 - 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. Device comprises 2N of logical units, N=2, 3, 4, …; a logical unit comprises the first, the second and the third input/output; the first input/output of logical unit J=1, 2, …, 2N is the input/output of J-th channel of the switching device; the second input/output of logical unit of odd number J=1, 3, 5, …, 2N-1 is connected to the second input/output of logical unit of the closest larger even number J=2, 4, 6, …, 2N; the third input/output of logical unit of odd number J=1, 3, 5, …, 2N-1 is connected to the respective third input/output of logival unit of even number J=2N, 2, 4, 6, …, 2N-2. Logical unit comprises a wave filter, multiplexed input/output of which is the first input/output of logical unit, the frist and the second demultiplexed input/output of the wave filter are the second and the third input/output of logical unit, respectively.

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

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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 2N logical blocks, N = 2, 3, 4, ..., the logical block contains the first, second and third inputs-outputs, the first input-output of the logical block with the number J = 1, 2, ... , 2N is the input / output of the Jth channel 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 2N logical blocks, N = 2, 3, 4, ..., the logical block contains the first, second and third inputs-outputs, the first input-output of the logical unit with the number J = 1, 2 , ..., 2N is the input-output of the J-th channel of the switch, the second input-output of the logic block with an odd number J = 1, 3, 5, ..., 2N-1 is connected to the second input-output of the logical block with the nearest large even number J = 2, 4, 6, ..., 2N, the third input-output of a logic block with an odd number J = 1, 3, 5, ..., 2N-1 is connected to the third input-output of a logic of the first block with the closest, even less modulo 2N, even number J = 2N, 2, 4, 6, ..., 2N-2, the logic block contains a wave filter, the multiplexed input-output of which is the first input-output of the logical block, the first and second demultiplexed inputs and outputs of the wave filter are the second and third inputs and outputs of the logic block, respectively.

In the proposed switch, wave filters operate with optical signals with wavelengths numbered in the form of the series λ1, λ2, λ3, ..., the wavelength increases uniformly as its number increases, the multiplexed input-output of the wave filter is transparent for optical signals with wavelengths with numbers λ1 , λ2, λ3, ..., the first demultiplexed input-output of the wave filter is transparent for optical signals with wavelengths λ1, λ3, λ5, ... and opaque for optical signals with wavelengths λ2, λ4, λ6, ..., the second demultiplexed leksirovanny input-output wave filter is transparent to optical signals with wavelengths numbered λ2, λ4, λ6, ... and opaque to optical signals with wavelengths numbers λ1, λ3, λ5, ...

Figure 1, a presents a simplified sketch of the design of the known [1] wave filter; figure 1, b is a variant of the transparency diagram of the wave filter; figure 1, in - examples of the paths of the passage of optical signals through a wave filter; figure 1, m is an example of the inclusion of a filter in a data transmission system. Figure 2 presents the most common options for the topology of computer networks; figure 3, a, b - functional diagram and diagram of the internal connections of the proposed four-channel optical signal switch; figure 4 is a functional diagram of the proposed 2N-channel switch of optical signals (N = 2, 3, 4, ...).

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, the filter is denoted by the letter F. 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 FIG. 1, b. 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 X-Y and X-Z filter channels. 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) is transparent to light with wavelengths λ1, λ3, λ5, ..., λ15 and opaque to 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) is transparent to light with wavelengths λ2, λ4, λ6, ..., λ16 and opaque to light with wavelengths λ1, λ3, λ5, ..., λ15.

Examples 6-11 of the optical signal paths through the wave filter (FIG. 1, e-z) show the propagation of a group of light signals through the filter F 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 10 (FIG. 1, g), the input-output X of the filter F 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.

In examples 12-14, shown in figure 1, and-l, all the conclusions of the filter are used.

Examples 12 and 13 show the possibility of using a filter F to interface unidirectional transmission lines of optical signals with bidirectional.

In example 12, 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 F 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 13 differs from example 12 in the directions of signal transmission through the terminals X and W of filter F.

In Example 14, all lines connected to the F filter are bidirectional. 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 F, wanting 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. If there is an intermediary device 15 (Fig. 1, m), 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 16 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 (15). According to preliminary "agreement" with this device, it immediately delivers the received pulses back to the input-output X, but uses light with a wavelength of λ13 for this. Filter F transfers these pulses to input-output Y, as required.

The given example shows the previously noted limited capabilities of the filter [1] when it is used as a functionally complete switch of optical signals in a computer network.

Figure 2 presents the most common options for the topology of computer networks. The topology of the type of "common bus" (figure 2, 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 17 to a common trunk 18. This is not technologically advanced, in addition, each splitter divides the energy of the signal fed into 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 19 (Fig.2, b) involves the presence of radial connections between the hub and the nodes 20 of the network. 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 20 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. 2, c), the nodes 21 are connected in a series closed circuit. The disadvantages inherent in the previously discussed networks (figure 2, 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 2, g). Outwardly, it resembles the previously considered network with a star topology (Fig. 2, b), but instead of a hub 19, it uses a switch 22 connected to nodes 23. Unlike a hub, the switch 22 is capable of combining optical fibers in a certain way connecting it with the nodes 23. For example, inside the switch, you can create connections in which the network has a ring logical structure similar to that shown in figure 2, c. Arrows 24 in FIG. 2, d correspond to packet transmission routes between nodes 23. As follows from the above diagram, packet transmission between nodes 23 occurs essentially along arrows 25, as in a network with a ring topology.

Isolation and bypassing of one or more faulty nodes 23 is carried out by the corresponding adjustment of the internal circuits of the switch 22 and does not affect the network nodes and communication lines.

The switch 26 [2] (Fig.2, d) contains 2N logic blocks 27, N = 2, 3, 4, ... Logical block 27 contains the first 28, second 29 and third 30 inputs / outputs, the first 28 input-output of the logical block with the number J = 1, 2, ..., 2N is the input-output of the 3rd channel of the switch. The inputs and outputs 28 of the logical blocks 27 are connected to the nodes 31 of the network. The input-output 30 of the logical block with the number J is connected to the input-output 29 of the adjacent logical block with the number J + 1 (J = 1, 2, ..., 2N-1), the input-output 30 of the logical block with the number 2N is connected to the input- output 29 of the logical block with the number J = 1.

Logic blocks 27 can be configured to transmit signals between nodes 31 in a ring circuit, as was shown in figure 2,

The proposed switch (four-channel version, N = 2, J = 1, 2, 3, 4), shown in figure 3, a, contains four identical logical blocks 32-35, each logical block contains the first 36, second 37 and third 38 inputs and outputs. The first inputs and outputs 36 of the logical blocks 32-35 are respectively the inputs and outputs 39-42 of the switch.

The second input-output 37 of the logical block 32 (34) with an odd number J = 1 (J = 3) is connected to the second input-output 37 of the logical block 33 (35) with the nearest large even number J = 2 (J = 4), the third the input-output 38 of the logical block 32 (34) with an odd number J = 1 (J = 3) is connected to the third input-output 38 of the logical block 35 (33) with the closest four least modular even number J = 4 (J = 2) , logic block 32 (33-35) contains a wave filter 1 (Fig. 1, a), the multiplexed input-output X of which is the first input-output 36 of the logical block, the first Y and second Z are demultiplexed the output inputs and outputs of the wave filter are respectively the second 37 and third 38 inputs and outputs of the logic unit.

When using the switch in a computer network, its nodes are connected to the inputs and outputs 39-42 of the first and fourth channels (J = 1, 2, 3, 4). For convenience of presentation, the channels are indicated in FIG. 3 by the letters A, B, C, and D.

To exchange data between network nodes, optical signals are used with wavelengths λ1, λ2, ..., λ16 uniformly distributed on the horizontal numerical axes of diagram 43 shown in FIG. 3, b. Adjacent wavelengths are separated by gaps of 100 nm.

In diagram 43, points 44 and arcs 45 between them display pairs of channels that use a given wavelength for bi-directional data exchange. From this diagram it follows that the network nodes connected to channels A and B exchange data using wavelengths λ1, λ3, λ5, ..., λ15. The same wavelengths are used for bi-directional data transfer between devices connected to channels C and D. Network nodes connected to channels A and D exchange data using wavelengths λ2, λ4, λ6, ..., λ16, which is displayed by elongated arcs 45 The same wavelengths are used for bidirectional data transfer between devices connected to channels B and C.

Thus, each node in the network can simultaneously and bilaterally exchange data with two nearest neighboring nodes using eight wavelengths in each of the transmit-receive directions.

In the General case, the proposed optical signal switch, shown in figure 4, contains 2N logic blocks 46-51, N = 2, 3, 4, ..., logical block 46-51 contains the first 52, second 53 and third 54 inputs / outputs ( corresponding signals are X, Y, Z), the first 52 input-output of the logic block with the number J = 1, 2, ..., 2N is the input-output of the J-th channel of the switch, the second input-output 53 of the logical block with the odd number J = 1, 3, 5, ..., 2N-1 is connected to the second input-output 53 of the logic block with the nearest large even number J = 2, 4, 6, ..., 2N, the third input-output 54 of the logical block with odd J = 1, 3, 5, ..., 2N-1 is connected to the third input-output 54 of the logic block with the nearest evenly smaller 2N even number J = 2N, 2, 4, 6, ..., 2N-2, the logic block 46-51 contains a wave filter, the multiplexed input-output of which is the first input-output of the logic unit, the first and second demultiplexed inputs and outputs of the wave filter are the second and third inputs and outputs of the logic unit.

As in the diagram in Fig. 3, a, corresponding to N = 2, neighboring nodes of a computer network exchange data using wavelengths λ1, λ3, λ5, ..., λ15 or λ2, λ4, λ6, ..., λ16 depending on the combination J channel numbers of the switch. In general, the number of wavelengths used is not limited to sixteen.

The application of the proposed switch of optical signals makes it possible to simplify the construction of networks with a logical structure of the ring type and star topology. The switch operates without a power source. The route of the packet transmitted by the network node is determined by the choice of wavelength (λ1-λ16), which allows you to simultaneously exchange information with neighboring nodes using 16 data streams.

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 2N logical blocks, N = 2, 3, 4, ..., the logical block contains the first, second and third inputs-outputs, the first input-output of the logical block with the number J = 1, 2, ..., 2N is the input-output of the J-th channel of the switch, characterized in that the second input-output of the logic block with an odd number J = 1, 3, 5, ..., 2N-1 is connected to the second input-output of the logical block with the nearest large even number J = 2, 4, 6, ..., 2N, the third input-output of a logic block with an odd number J = 1, 3, 5, ..., 2N-1 is connected to the corresponding third input-output ohms of the logic block, an even number J = 2N, 2, 4, 6, ..., 2N-2, the logic block contains a wave filter, the multiplexed input-output of which is the first input-output of the logical block, the first and second demultiplexed inputs and outputs of the wave filter respectively, the second and third inputs and outputs of the logical unit. 2. The optical signal switch according to claim 1, characterized in that the wave filters 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, the multiplexed wave input-output the filter is transparent for optical signals with wavelengths λ1, λ2, λ3, ..., the first demultiplexed input-output of the wave filter is transparent for optical signals with wavelengths λ1, λ3, λ5, ... and opaque for optical signals with wavelengths but erami λ1, λ4, λ6, ..., demultiplexed second input-output wave filter is transparent to optical signals with wavelengths numbered λ2, λ4, λ6, ... and opaque to optical signals with wavelengths numbers λ1, λ3, λ5, ...

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