RU2515958C1 - Method of switching nxn optical channels and multichannel switch (versions) - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: at each channel assembly step, control electrical signals are transmitted to corresponding pairs of total internal reflection cells simultaneously and in parallel for all discharges in order to change the refraction index of material of said cells and, consequently, to transmit optical flux to a neighbouring waveguide. To implement the method, a multichannel switch is disclosed, the switching circuit of which is staged and branched, with parallel connection of input and output optical channel in each stage. Connection addresses are set using lines of optical modulators. The number of channels is doubled using an optical splitter, and transmission of signals from channel to channel is carried out by transmitting electrical signals to the total internal reflection cells. In the first version of the device, signals are directed into cells by electrodes connected thereto, and in the second version using an array of light emitters and optical isolators.

EFFECT: connecting input and output optical channels without crossing fibre-optic and electrical cables with maximum parallelism.

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Description

Technical field

The invention relates to the field of information processing and communication and can be used to transmit, receive and redistribute information signals in switching devices of multi-subscriber telecommunication and fiber-optic communication systems and integrated optics systems, information processing and data calculation, including in supercomputers.

State of the art

A known method of switching K × M optical channels and a fiber optic switch K × M optical channels with a relatively low attenuation in the channels and a low level of crosstalk [1]. The switch contains a plate of an electro-optical crystal of lithium niobate, in which waveguide channels with control electrodes are made. Each plate is divided into M cells, K waveguide channels are made in each cell, i.e. all performed K × M channels. From each of the K inputs is M optical cables, one for each cell. To each of the M outputs, on the contrary, all K optical cables are connected from the corresponding cell: from the first cell to the first output, from the second cell to the second and so on. From the series connection of the first of K inputs with all M outputs, then the second input with all M outputs, then the third, fourth, etc. up to the connection of the Kth input with all M outputs, a significant drawback arises, namely: the switch has a large number of intersecting fiber optic cables, as well as electrical wires for connecting control electrodes, which complicates its design and technological implementation.

The known method of multi-stage switching N × N channels and a switch that forms the so-called Banyan network, related to the well-known MIN switching networks (from the Multistage Interconnection Network), which are built by forming cascades of switching elements [2]. In this case, the main switching basis of the Banyan network (“cross”), consisting of 2 × 2 elements, processes the input signal in accordance with the value of the discharge address, and if this discharge is zero, the signal is sent to the upper output port of the cross, and Otherwise, to the bottom.

Banyan networks are blocking schemes, and the likelihood of signal blocking during routing increases rapidly with network growth [3]. In the event of a conflict of routes between two signals addressed to different output ports, only one of the two signals can reach the next stage, as a result of which the overall performance of the switching process decreases. Adding a pre-sorting cascade, for example, the so-called Butcher sorter, avoids such locks, but if signals are simultaneously addressed to the same output, buffering becomes the only solution [4].

The closest analogue (prototype) of the proposed device is a multi-channel switch, made by the method [5] of switching N × N optical channels. The method provides that in an N × N switch:

- bitwise, starting with the highest order of addresses, an optical connection of N input optical channels with N output optical channels is organized;

- all optical connections of N input optical channels with N output optical channels are performed in n stages (steps), where n = log × N is the number of bits of addresses;

- all optical connections in each category of addresses are performed in parallel;

- at each stage, the operation of doubling the channels is performed, namely, at the first stage, channels with 0 and 1 in the highest order of all addresses are separated, at the second stage, channels with 0 and 1 are separated in the next order of addresses, etc., so at the last the stage separates channels from 0 and 1 in the lower order of all addresses;

- at any stage after the operation of doubling the channels in each of the two route arms (from 0 and 1 in this category of addresses), the operation of double channel multiplexing (assembly) is performed by removing gaps, i.e. “Empty” (without an optical signal) channels, and a compact (adjacent) arrangement of signal channels, i.e. channels that will be required for the passage of switched optical streams.

The multichannel N × N switch [5] is fiber-optic and provides the connection of any input channels with any output channels. It contains an active element of lithium niobate with waveguide channels, control electrodes and fiber optic cables connected to it. The switching circuit is cascaded and branched, with a series-parallel connection of N input optical channels with N output optical channels in n stages. Addresses for connecting the N input optical channels to the N output optical channels are set using lines of optical modulators. To realize doubling, special translucent mirrors or cubes made up of two prisms are used.

In order to double channel compaction after doubling, pairs of electro-optical total internal reflection prisms are used, which transfer the signal from the waveguide to the adjacent waveguide when a control voltage is applied to the corresponding contacts. To do this, at each stage, using the line of photo sensors in the channels, the presence or absence of an optical signal is recorded and electrical feedback signals are generated to control the change in the conditions of total internal reflection in the waveguide channel. The optical channels are connected at a small (test) level of the optical signal, sufficient for photodetectors to register it in the feedback system, for which a separate light source or a small part of the optical information stream is used, and the main information light stream is supplied to the switch after completion of the channel connection process, those. after installing all the air defense cells in the appropriate transmitting or deflecting light state.

The disadvantages of this switch are:

- the presence of feedback, necessitating the preliminary configuration of the switch at a low level of the optical signal and requiring for its implementation at each stage N photosensors;

- an increase in the connection time of the channels as a result of multi-stage generation of feedback signals.

The problem to be solved in the proposed method and device for switching N × N optical channels is to make input and output optical channel connections in automatic mode without intersecting fiber-optic and electric cables and with maximum parallelism, but with a multiple reduction in channel connection time due to the lack of feedback and all photosensors.

Brief Description of the Drawings

The drawings show: Figa and 1B is a diagram explaining the operation of a multi-channel switch according to the method [5].

Figure 2 - The proposed control scheme for pumping the flow of information from one optical channel to another using a pair of air defense cells: a - for the first embodiment, providing electrical control, in - for the second embodiment, providing optical control.

Figure 3 - Diagram of the implementation of the operation of the "Assembly" of the channels (for example, 8 channels) using the air defense cells; gray indicate the cells to which the control voltage is applied simultaneously.

Figure 4 - The proposed General diagram of the switch (for example, 8 channel device) located:

a - in the initial state, when the input and output channels are not connected;

in - in the final state, when the information optical flow is directed to the given addresses.

SUMMARY OF THE INVENTION

The solution to this problem is ensured by the fact that in a multichannel switch made according to the method [5] and providing the connection of any input channels with any output channels without intersections of fiber optic and electric cables and with maximum parallelism, including devices for addressing signals, devices for doubling optical flows, an active element with waveguide channels, as well as controls for changing the refractive index of the material of the waveguide channel, new is that

- remove all lines of photosensors from the device, recording the presence or absence of an optical signal and generating electrical feedback signals to determine the places of application of electric voltage to the air defense cells, converting the optical stream from one waveguide to another (neighboring),

- using a computer at the input and specified addresses, calculate all the pairs of air defense cells necessary to complete the signal assembly at all stages,

- signal assembly is performed simultaneously at all stages, i.e. immediately for all bits of addresses, with parallel electrical control (first option) or parallel optical control (second option) by switching the air defense cells,

why in the first embodiment, providing electrical control, the electrodes connected to the electrodes associated with the calculated (switchable) air defense cells simultaneously and simultaneously for all address bits are necessary to change the refractive index of the material of the air defense cells in these places and, accordingly, for converting an optical stream to an adjacent waveguide according to the conditions of the total internal reflection effect,

and in the second embodiment, providing optical control, in

optocouplers are introduced into the device, each optocoupler being electrically connected to its own air defense cell, so that the number of optocouplers is equal to the number of air defense cells, a matrix of light emitters (MIS) is introduced, the wavelength of which lies in the sensitivity region of the optocouplers, and projection optics, through which an array of optical signals array formed in the MIS, geometrically uniquely associates an array of optocouplers electrically connected to the air defense cells, and in the MIS include light emitters optically and geometrically connected to those optocouplers for operation mi from which the electric voltage generated by optical excitation is supplied to the calculated (switchable) air defense cells, and, in addition, an optical mask and / or holographic optical element (GOE) are optically coupled to the MIS and optocouplers and matching the configuration optical beams emerging from the MIS, with the configuration of the photo-receiving sites of the optocouplers.

On figa shows a diagram explaining the example of a three-digit (8-channel) device switching method in the proposed multi-channel switch at different stages of the connection of the channels. Here 1 is a line of input optical channels with given switching addresses; 2 '- the line of direct and inverse modulators (filters), specifying at the first stage (belonging to it is indicated by one stroke), after doubling the channels, the transmission of optical signals in accordance with 0 and 1 in the high order of addresses; 3 'is the result of the removal of gaps in the first stage of the connection of the channels; 2 "- a line of direct and inverse modulators (filters), specifying in the second stage (belonging to it is indicated by two strokes), after doubling the channels, the transmission of optical signals in accordance with 0 and 1 in the second category of addresses; 3" - the result of removing gaps on the second stage of connecting the channels; 2 "'- the line of direct and inverse modulators (filters), specifying in the third stage (belonging to it is indicated by three strokes), after doubling the channels, the transmission of optical signals in accordance with 0 and 1 in the lower order of addresses; 3" - the result of removing the gaps at the third stage of connecting the channels, bringing each of the 8 input optical signals to the selected address.

From the diagram in figa shows that all channel connections according to the claimed method are performed in parallel, not only within each category of addresses, but almost simultaneously for all categories. Thus, the essence of the proposed method consists in such a connection of channels, which provides conditions for making connections of input and output channels with maximum parallelism.

You can also notice that the proposed method is quite universal and can be used in multichannel switches not only optical but also electrical signals.

To implement the method, an optoelectronic multichannel switch is proposed, containing waveguide channels with control electrodes, made on the basis of an electro-optical lithium niobate crystal with built-in air defense cells and, thanks to the air defense effect, providing a specified connection of any optical input with any optical output, in which, in comparison with the prototype, a new one It is that there is no need for the use of photoelectronic feedback and additional tuning light transmission.

Wherein:

- the addresses for connecting the N input optical channels to the N output optical channels are set using lines of optical modulators,

- for the implementation of doubling, special translucent mirrors or cubes made up of two prisms are used,

- to transfer signals from the waveguide to the waveguide during channel compaction, air defense cells are used, to which the control electric signals arrive in parallel:

in the first version, from a voltage source with the number of all outputs equal to the total number of air defense cells, and with the number of outputs open for voltage equal to the number of simultaneously switched air defense cells calculated by a computer; in the second variant, from optocouplers excited optically by means of MIS, in which the number of emitters is equal to the total number of air defense cells, and the number of emitters included in the operation is equal to the number of simultaneously switched air defense cells calculated by a computer.

The technical result achieved in the claimed invention is that the design of the optoelectronic switching device N × N optical channels, based on a cascade, branched and maximally parallel connection scheme and using signals from a computer to control the total internal reflection in the required places, provides a given connection any input and output channels without intersections of fiber-optic and electric cables, with greater parallelism, in a shorter time and without using anija adjusting transmittance of light of low power, making the device manufacturable.

The main advantages of the proposed method and device for switching N × N optical channels in comparison with the prototype in the end are:

- making connections at all stages in parallel in automatic mode with the one-time formation of control electric signals to the electrodes of air defense cells using a computer, which change the refractive index under the influence of the signals;

- the absence of the tuning stage, when the optical signal is connected at a low level of the optical signal sufficient for its detection by photodetectors in the feedback system, moreover, a separate light source or a small part of the optical information stream is used for this, and the main information light stream is supplied to the switch after completion of the process of connecting the channels, i.e. after the installation of all air defense prisms in the appropriate transmitting or deflecting light state;

- due to the above, a multiple reduction in the connection time of the channels;

- unlike a banyan-network type switch, the proposed device does not need to use such additional cascades as a buffer or sorter, because here conflict situations (internal blocking) are eliminated due to the initially correct setting of addresses and calculation of routes using a computer, as well as the result of the complete parallelism of the switching process in each cascade, achieved by separating routes with a “zero” and “single” discharge of addresses for all routes at once, and not for each individually.

Thus, the proposed method and device using air defense cells in waveguides allows one to obtain a predetermined connection of any input and output channels in a multichannel switch without using photoelectronic feedback and an additional tuning stage, as parallel and fast as possible.

The advantage of the first embodiment, using electric control of the refractive index of the material of the air defense cells, in comparison with the second, using optical control, is a smaller number of structural elements (there are no MIS, projection optics, GOE or optical filter), which facilitates the design and technological implementation of the switch. On the other hand, the advantage of the second option, with the control of air defense cells from autonomous optocouplers, is the lack of a common electrical control circuit and the possibility, using the just mentioned structural elements, to introduce additional switchboard control functions into the switch.

To improve the characteristics of the claimed optoelectronic switch (without changing its architecture) in the future, individually or in combination, you can use various options for waveguide, integrated optical or prismatic air defense cells. In addition to the principle of air defense, to transfer an optical signal from one waveguide channel to another in a given arm of the Y-coupler, one can use a change in the refractive index controlled by an electric signal (for example, by means of a transverse electro-optical effect). A change in the refractive index in the arms of the Y-couplers can also be initiated by an optical signal if the waveguide material is photorefractive. As optical splitters, you can use translucent mirrors, dual prism optical cubes, holographic optical elements and other elements of the same purpose. In the lines of high-speed and compact optical modulators, it is possible to use modulators not only from lithium niobate, but also based on other electro-optical materials, including integrated-optical, micromirror, semiconductor (for example, based on the Franz-Keldysh effect) and other modulators of the same destination. In multi-bit switches, it is possible to provide amplification of optical flows (with preservation of their information characteristics) using compact semiconductor lasers and matching elements.

Industrial applicability

The proposed optoelectronic switch based on air defense cells is a technological and efficient device for switching N × N optical channels. This makes it possible to use it in many modern and promising systems for the transmission, reception and redistribution of information signals, in telecommunication systems, in multi-device devices and information processing and data calculation systems, including in supercomputers, in fiber-optic and integrated-optical communication systems .

An example embodiment of the invention

According to the proposed method, the operation of an optoelectronic multi-channel switch with a connection of 8 × 8 optical channels was modeled.

Figv illustrates the operation of such a switch. At the first stage, operations of doubling the channels {1 '} were performed with separation by 0 and 1 in the highest order of addresses and the operation of channel multiplexing {2'} in both arms, i.e. assembly of signal channels and removal of those channels in which the signal is absent. As a result, 4 signal channels remained in both arms. At the next stages, the same operations were performed for subsequent bits of addresses, as a result of which, at the second stage {1 ", 2"}, 4 arms were formed with 2 signal channels, and at the third stage {1 '", 2"'} - 8 arms on 1 signal channel leading the light signal to the selected address.

It is clear that if there are N = 2 ⁿ channels in n stages, all N channels can be switched to the given N addresses. Accordingly, for the common 64-bit and 128-bit switch, the number of stages is 6 and 7.

In the model used, as in the prototype [5], the number of channels was doubled using an optical splitter, and their separation by 0 and 1 was performed using an inverse optical filter. As optical splitters, optical cubes composed of two prisms were used. Pairs of rulers of modulators, one of which has always been an inverter, i.e. set not single, but zero bits of addresses, were performed on the basis of electro-optical crystals. Including those or other modulators, it was possible to selectively transmit light, thereby addressing the signals.

Figures 2a and 2c show the schemes used in the model for pumping the flow of optical information from one channel to another according to the first embodiment, providing electrical control (Fig. 2a), and the second embodiment, providing optical control (Fig. 2b). To explain the pumping process in the first embodiment (figa) we consider two optical waveguides A and B, closely spaced to each other. They have built-in pairs of air defense cells 1-2 and 3-4, to which control electrodes are connected (electrode a to cell 1, electrode in to cell 4). Let one of the waveguides (A) be open and an information flow propagate in it, and the adjacent waveguide (B) be closed, i.e. “Empty” (case I). Using the input and specified output addresses, the computer determines in which places the optical stream needs to be transferred to the neighboring empty channel, and sends signals to the generator to connect the control electrodes a and b. The voltage applied to the electrodes in turn leads to a change in the refractive index of electro-optical cells 1 and 4, and due to the effect of total internal reflection, the cells reflect light into an adjacent waveguide. In another case (case II), when both waveguides are open to an optical signal, the refractive index of the air defense cells does not change, and information flows continue to propagate through their channels.

To explain the second embodiment (Fig.2c), we also consider two optical waveguides A and B, closely spaced to each other with pairs of air defense cells 1-2 and 3-4 embedded in them. Air defense cells 1 and 4 are electrically connected to optocouplers (each cell has its own optocoupler). Optocouplers control optical signals are fed using a matrix of light emitters (MIS), which, in turn, is controlled by a computer. As in the first embodiment, the figure shows two cases: case I, when one of the waveguides (A) is open and the information flow propagates in it, and the adjacent waveguide (B) is closed, i.e. “Empty”, and case II, when both waveguides are open to an optical signal. In case I, at the input and given output addresses, the computer determines in which places the optical stream needs to be transferred to the neighboring empty channel, and sends signals to the MIS, which, in turn, sends optical signals to the corresponding optocouplers so that they generate electrical signals for switching on necessary air defense cells. In case II, the refractive index of the air defense cells does not need to be changed, so the computer does not generate any signals.

Figure 3 shows how air defense cells should be located in the waveguide in order to realize a "self-controlled" assembly in one of the switch arms at the first stage with 8 channels for any combination of the presence of signals in them.

The assembly of the channels was carried out as follows. Using the input and specified output addresses, the computer determines which air defense cells should be turned on and sends signals to the corresponding electrodes (in the first embodiment) or to the corresponding MIS (in the second embodiment). The electrodes themselves, MIS, optocouplers and computers are not shown in the figure. For a specific combination of input signals in one of the arms of the switch (Fig. 3), the included cells are painted gray. When the air defense was turned on, the light was reflected at an angle of 90 ° into the adjacent waveguide, and then it turned at the same right angle to continue its propagation along another waveguide. In this way, all the “empty” channels were removed, and at the output of the first cascade only 4 (out of 8) signal channels were located in two arms, and at the output of the second cascade in four arms only 2 (out of 4) located signal paths channel.

Figure 4 shows the general diagram of a multi-channel switch with 8 × 8 channels in a - initial (channels are not switched) and in b - final states (channel switching is completed, and the information light flux propagates through them). The optoelectronic switch according to the claimed method and device contained optical shutters 3, made on the basis of light modulators, which are the input ports of the switch; translucent cubes 1 ', 1 ", 1", composed of two prisms; line modulators 2 ', 2 ", 2"', used for addressing signals; controlled air defense cells 5 ', 5 ", embedded in the waveguides 4. For each combination of light beams at the input, the computer applied various, pre-programmed combinations of control signals to the electrodes (a and c in Fig.2a) or to the MIS (Fig.26), which in turn included the corresponding air defense cells 5 ', 5 ". Outgoing commutated streams are indicated by 6 in the figure.

It should be noted that not all cells require control of signals from a computer. In the first four channels (if counted from the bottom in FIG. 4), the refractive index of the material of the air defense cells was changed to reflect the optical signal into the adjacent waveguide or to pass it through. And in the channels from the fifth to the eighth, the refractive index did not change and was always in the “on” state, i.e. reflected the optical signal, because Optical signals traveling through these channels should always be converted to neighboring ones during assembly. In these compounds, for example, a reflecting mirror or a prism can also be provided.

Information sources

1. Geokchaev F.G. Multichannel fiber optic switch // RF Patent No. 2107318 (1998).

2. Maksimov N.V., Partyka T.L., Popov I.I. The architecture of computers and computing systems // M .: FORUM-INFRA-M, s.316-317 (2005).

3. Zakharov G.P., Simonov M.V., Yanovsky G.G. Services and architecture of broadband digital integrated service networks // M .: Eco-Trends, 102 pp. (1993).

4. Efimushkin V., Ledovskikh T. Switching in ATM networks // Networks, No. 1, pp. 26-31 (2000).

5. Kompanets I. N., Kompanets S. I., Neevina T. A. The method of switching N × N optical channels and a multi-channel switch // RF Patent No. 2456652 (2012).

Claims (3)

1. A method of switching N × N optical channels in a multi-channel switch based on the optical connection of any given input optical channel to any given output optical channel by organizing a bitwise, starting from the highest order of addresses, optical connection of N input optical channels with N output optical channels, which is performed in n stages (steps), where n = log ₂ N is the number of bits, and all optical connections in each bit of the addresses are performed in parallel, at each stage the operation of doubling the number of optical channels with the inversion of the discharge values in one of the arms, and after the doubling operation, the channel compaction (assembly) operation is performed by removing channels without an optical signal, characterized in that
- at each stage, when performing the operation of assembling the channels, the corresponding electrical pairs are applied simultaneously and parallel to all discharges to the corresponding pairs of cells of total internal reflection (ATR) to change the refractive index of the material of these cells and, accordingly, to transfer the optical flux to an adjacent waveguide,
- cells to which electrical signals must be supplied are determined by computer at the input and predetermined output addresses, and
- according to the result of the calculations, the control electric signals are fed directly to the electrodes of the air defense cells or the electrical signals are converted in the matrix of light emitters (MIS) into optical signals that excite optocouplers electrically connected to the switched air defense cells. 2. A multi-channel switch comprising an active element of electro-optical material with waveguide channels, in which the addresses for connecting the N input optical channels to the N output optical channels are set using lines of optical modulators, the doubling of the optical channels is performed using an optical splitter containing electro-optical cells of a complete internal reflection (AD) for transferring signals from one optical channel to an adjacent optical channel during channel compaction and an electric voltage source with the number of all exits equal to the total number of air defense cells, characterized in that
- an electronic processor has been introduced into the switch, which calculates at the input and specified output addresses those air defense cells to which it is necessary to simultaneously supply control electric signals during channel compaction,
- the number of outputs open for electrical voltage is equal to the number of simultaneously switched air defense cells calculated by the electronic processor. 3. A multi-channel switch comprising an active element of electro-optical material with waveguide channels, in which the addresses for connecting the N input optical channels to the N output optical channels are set using lines of optical modulators, the doubling of the optical channels is performed using an optical splitter containing electro-optical cells of a complete internal reflection (air defense) for transferring signals from one optical channel to an adjacent optical channel during channel compaction, characterized in that
- a matrix of light emitters (MIS) is introduced into it and an matrix of optocouplers equivalent to it in terms of the number of elements, optically coupled to the MIS and electrically connected to the air defense cells, moreover, in the optocoupler matrix under the influence of radiation from computer-defined emitters, electrical signals are generated to control the switching of the air defense cells;
- projection optics are introduced into it, with the help of which the array of optical signals generated in the MIS is geometrically uniquely associated with the array of optocouplers electrically connected to the air defense cells;
- an optical mask and / or a holographic optical element (GOE) are introduced into it, optically coupled to the MIS and optrons and matching the configuration of the optical beams emerging from the MIS with the configuration of the photodetector areas of the optocouplers.

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