JPH0113791B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION State of the Art The invention relates to a method for controlling opto-electric coupling points of a switching device according to the preambles of claims 1 and 9. The prior art of this type of process, which is the starting point for the present invention, is the following unpublished patent specification (1) German Patent Application No. 3147109 (2) German Patent Application No. 3138979 Specification (3) Specification of Federal Republic of Germany Patent Application No. 3138980 and the following published documents (4) Electronics Letters 10 (February 21, 1974) No. 4, pp. 41 to 43 (5) Electronics Letters 12 (October 28, 1976) No. 22, pages 575 to 577.

Other optical switches including transistors or diodes on a first substrate or a second substrate and their control are known, for example from the following numerous documents:

(6) Electronics Letters 12 (September 2, 1977) No. 18, pp. 459 and 460 (7) Applied Physics Letters 25 (October 15, 1974) No. 8, Nos. 458 to 460 Pages (8) Applied Physics Letters 25 (November 15, 1974) No. 10, No. 561, 562 (9) Applied Physics Letters 27 (August 15, 1975) No. 4, No. 202 Applied Physics Letters 27 (September 1, 1975) No. 5, pp. 289 to 291 (11) Applied Physics Letters 28 (May 1, 1976) No. 9 , pp. 503-506 (12) Applied Physics Letters 31 (August 15, 1977) No. 4, pp. 266, 267 (13) IEEE J. of Quant EI QE-12 (1976) July) No. 7, pp. 396-401 (14) Integrated Optics Salt-
Lake City Utah (January 12-14, 1976)
MA4-1 to MA4-3 That is, a number of optical switches of this type formed on one or more substrates can be used as a joining point of a switch frame with optical links in a telephone switching system, This point is particularly described in the above-mentioned documents (1) to (5).

This type of optical switch can be used equivalently as a switch for optical signals instead of a 2.times.2 switch in a switch frame for purely electrical signals. Thus, for example, the switch is already known from the following publications:

(15) U.S. Patent No. 3638193 (16) U.S. Patent No. 3593295 (17) Federal Republic of Germany Patent Publication No. 1922891 (18) Federal Republic of Germany Patent Publication No. 2036128 (19) Federal Republic of Germany Patent Publication No. 2036176 and (20) BELL-System Technique J. 1968,
May-June, pp. 813-822 The invention starts from the following method for controlling optoelectric coupling points known from the above-mentioned literature. Namely, a method for controlling an opto-electric coupling point of a switching device having a link, which is a light conductor path, for transmitting an optical signal, the coupling point forming an optical switch manufactured in integrated technology on a substrate, In addition, the light switch each includes at least two adjacent, mutually parallel first and second light sections, the light stream being input into the first light section of the light sections. controlled by a control potential acting on the light section, i.e. the light flow input into the first light section of the light switch is coupled into the second light section or not. At least one electrically conductive electrode is provided in each case as a control electrode of the light switch along each light section of the light guide track which is held in the first light section and which is formed on the substrate in integrated technology. the control electrode is configured to apply a control potential to the light section and to apply one or more electrodes to the light section in order to switch the light guided into the light section as required by means of its potential and thus the electric field. an electric field generator supplies a suitable control potential to the relevant electrode of the optical switch, and a polarity change command detector and the one or more electric field generators controlled by the polarity change command detector The polarity of the electric field is switched by the control potential that acts on the light section of the light section.

Such a conventional optical switch will first be explained in detail with reference to FIG.

FIG. 4 shows two known light guide paths LL, namely a first light section A--A' and a second light section B--.
A light switch LK with B' is shown. The light switch in this case includes a light conductor track LL which is arranged closely parallel over a length of approximately 3 mm, as well as eight electrically controllable electrodes E11...E24. The latter are arranged in pairs, one behind the other with a parallel section of the light guide path LL in between, and each alternately controlled by a first control potential V1 and a second control potential V2. controlled. The insulating layer Is has a conductive path for the control potential V1 and a conductive path for the control potential V2.
spatially separate the conductive paths. These control potentials V1, V2 control the speed of light in the light guide LL in a manner known per se. At a specific value of control potentials V1 and V2, that is, control voltage V1/V2, from the optical signal input side A to the optical signal output side
A cross-coupling is performed in which the signals to B' and from the optical signal input side B to the optical signal output side A' are connected in a crosswise manner, with high Allow attenuation to occur.

The optical switch LK shown in FIG. 4 can be made of GaAs or
It is formed on a first substrate made of LiNbO ₃ . The light conductors are each provided with at least one electrically controllable, electrically conductive electrode E11...E24 for controlling the light switch LK. By means of control potentials, here V1 and V2, the electrodes are controlled so that the light guided into the respective light guide path LL forms a linear connection from A to A' to B to B' or the light guide A cross-connection is made between the paths LL, ie from A to B' or from B to A'.

However, this type of photoelectric light switch is described in the literature (5).
It has the following drawbacks, which are well known and often hinder: This means that the control voltage, or the control potential of the control voltage, must often be precisely adjusted in order to achieve optimum operation, and, according to literature (5), rapid aging of the light switch can occur.
In order to avoid or compensate for this, it is necessary to continuously reverse the polarity of the electric field of the electrodes or in any case to change the potential of the electrodes substantially continuously, each time for example every 500 ms. This means that if the control voltage is not set sufficiently precisely, the crosstalk attenuation between the different light guides of the light switch and possibly the entire first substrate will have an adverse effect, or the Other pass-through damping acts adversely.

The use of such optical switches as connection points in (telephone) exchange systems with purely optical links places particularly high demands on the crosstalk attenuation on the one hand and the through attenuation of the light guide paths on the other hand. Moreover, constantly increasing the potential of the electrodes in continuous operation of the connection points of the exchange device is extremely expensive and cannot be tolerated. This is because in exchange devices of this type, it is difficult to guarantee reliable operating conditions that are easily reproducible at all times due to the strict tolerances required of the device.

OBJECTS AND EFFECTS OF THE INVENTION In view of the above-mentioned points, the present invention makes it possible to minimize the interruption of the connection path during switching operations and aging compensation. This object is solved by the features of claims 1 and 9. This is done, inter alia, by cleverly synchronizing the polarity reversals of all possible connection points through which the connecting paths are connected. At that time, the value of the control voltage applied between the electrodes at the connection point during the "rest" period is the value of the control voltage between the electrodes during the period when the optical signal is transmitted through the connection path. It can be selected differently, for example higher. The shorter the pause time compared to the transmission duration, the higher the value of the control voltage during the pause period should be compared to the value of the control voltage during the transmission period. By correspondingly selecting the value of the control voltage during the "rest" period during which the polarity reversal takes place, the corresponding connection path during the polarity reversal is can be blocked or can be in a state with low crosstalk attenuation. By carefully selecting the control voltage and the connection time ratio between "transmission" and "pause" in each case, the same connection path is connected during the "pause" period as during the transmission period, so that the polarity of the electric field in question is reversed. Additional, low-crosstalk transmissions over the same connection are also possible during the "pause" periods in which the connection is performed. However, this "pause" can be used only for transmitting dial tones, dial pulses, charging pulses and other data for controlling and monitoring the switching equipment.

The arrangement described in the embodiment section of the patent claims provides the following additional advantages.

According to the structure recited in claim 2, when the coupling points of the connection path are distributed on a plurality of substrates and a plurality of separately operating electric field generators generate an electric field to each corresponding electrode. However, it becomes possible to guarantee synchronization of polarity reversal at all connection points of the connection path.

The arrangement according to claim 3 makes it possible to synchronize the control of the electric field generator with particularly low hardware costs.

According to the configuration described in claim 4,
It becomes possible to quickly and easily supply the electrodes at different bonding points with particular potentials, the optimum height of which varies from bonding point to bonding point due to manufacturing deviations. .

According to the configuration described in claim 5, it becomes possible to perform more accurate compensation, that is, to avoid aging of the connection points.

According to the structure recited in claim 6, the above compensation can be further improved.

According to the configuration recited in claim 7, the duration of the pause can be selected differently from the duration of the transmission.

According to the configuration described in claim 8,
The "pause" periods are made available for low crosstalk transmission of information modulated signals.

According to the configuration described in claim 10,
By using different flash pulses for polarity switching in one direction and for polarity switching in the other direction, the duration of both polarity switching phases can be determined.
In particular, different magnitudes can be selected for each flash pulse. This means that, in particular, by varying the duration of the polarity switching phase,
In order to be able to adjust the attenuation in the non-through-connected direction of the light switch to a particularly high degree synchronized by the flash pulses, claim 6
It is advantageous in combination with the special configurations described in Sec.

According to the structure set forth in claim 11, since no information is transmitted in the time slot following the flash pulse, loss of information can be avoided.

The arrangement according to claim 12 makes it possible to couple in a flash pulse in a particularly simple manner.

According to the configuration described in claim 13,
In a particularly simple manner, flash pulses, ie polarity switching commands, can be detected quickly and reliably from the entire transmitted optical signal train.

DESCRIPTION OF EMBODIMENTS Next, the method of the present invention will be described with reference to embodiments and drawings.

Figure 3 shows how a pure optical signal OS can be transmitted, for example, through a number of optical fibers installed on the input and output sides.
An example of a device for realizing a method for controlling a photoelectric coupling point S of an exchange system, which transmits data between LL, is as follows.
Shown in relation to FIG. Here, the link L located between the coupling points S and the lead LL attached to the switch frame connecting terminal are each not a conductive line but a light guide path for guiding an optical signal. The connection points S are each formed in integrated technology on one substrate, which can be made of GaAs or LiNbO ₃ , for example, or are provided distributed over a plurality of substrates of this kind. The coupling point S is formed by an optical switch as follows. That is, the optical switch comprises electrically controllable electrodes for switching the optical signal os, known as already mentioned, and furthermore, the electric field in question changes the speed of light in the optical conductor path L in question. This optical switch is adapted to control the switching state of this optical switch S, which uses an electric field by means of an electrode to influence the optical conductor path L formed in integrated technology on the substrate. .

This occurs in order to avoid relatively long-lasting interruptions of the interconnects to be interconnected and to reduce the potential between the different optical switches as much as possible during the actual interconnection of the interconnects. Mutual interference, which is a hindrance to optical switches, can be reduced in the following manner. That is, the polarity of the electric field of at least some of the electrodes is changed periodically, for example every 100 ms or only after 500 ms, for the duration tx of the rest period p.
and at least approximately change the polarity of the electric field at all connection points S formed on the same substrate of the through-connected connections, at least approximately:
It is synchronized by an optical polarity switching command vb transmitted by an optical signal os, and is thereby inverted. The relevant polarity switching command vb can control not only the polarity reversal in a single connection path, but also the synchronization of the polarity reversal in a large number of such connections. The interruption of the connections during this period for completely or at least significantly reducing aging is correspondingly synchronized and therefore lasts for a relatively short time. By synchronously reversing the polarity of all the spatially adjacent connecting paths or as much as possible, all the optical switches S are treated so that they do not age at the same time, so that the adjacent optical switches S
The potential difference between them is in each case small, so that mutual interference is small. In this case, the optically transmitted polarity switching command allows each of these systems to be Synchronization of polarity reversals in all switching devices can be performed even when controlled by a unique computer for pathfinding.

A portion of the energy of the optical signal os, e.g. 1%
A, polarity switching command VB to control the synchronization of polarity reversal
from the transmitted optical signal os from a feed-through connection (e.g. by means of a correspondingly controlled optical output coupler RK, which operates as a directional coupler). be able to. As can be seen in FIG. 1, the optical signal os advantageously typically contains a special digit sequence vb of relatively long character, for example a sequence of only 1 bit or a sequence of only 0 bits or a sequence of only 10000001 bytes. not present. Nevertheless, it is coupled out from the connection path and identified in the detector Det, e.g.
This kind of relatively long special digit string vb connected for 300 ns has at least the polarity for the reversal of the polarity of the electric field of the electrode for the optical switch S on the substrate in question along the connection path in which it is connected through. This is the switching command vb. That is, according to FIG. 1, during the pause period p after the polarity switching command vb between the two transmissions of the optical signal os modulated by the subscriber information inf, the electric field generator or potential generator
A corresponding reversal control of Co reverses the polarity of the electric field at the electrode in question. In this way, at advantageous values of the potential ci generated by the generator Co, the aging of the light switch in question is completely or significantly reduced. Therefore, each pause period p divides the transmitted optical signal os modulated by the subscriber information inf into blocks of approximately the same duration, e.g. Divide into blocks of 500ms duration. 500ms is the optimum value found as a result of experiments.

Depending on the format of the polarity switching command vb, especially the column
Depending on the type of vb, different methods can be applied to identify the polarity switching command vb in the detector Det. The following method involves particularly low costs. That is to say that the optical signal os modulated by the subscriber information inf and transmitted at a bit rate of, for example, 200 MHz is modulated according to the HDB3 code well known in digital transmission technology and advantageously contains identical (i.e. 0 bits) (can consist of only one bit or only one bit)
This is a method of transmitting data just before the start of the process. That is, in that case, the output coupled optical signal train vb is transferred to the photoelectric converter
an output signal of a synchronously operating oscillator, which is converted in Opt/El into an electrical signal train vb and in the detector Det, which can be, for example, a component of the detector;
Comparisons are made using logic circuitry that checks for matches and digit patterns. This comparison is carried out on the one hand when the signal sequence vb contains only the same digits, for example one bit, and when the oscillator
This is particularly simple if synchronization is forced at the start of vb by the time clock of the digits of this signal train vb. The comparison result, ie the output signal of the logic circuit, can be counted in a counter of the detector Det, in which case the signal sequence
If a counting result exceeds a limit value corresponding to the length of vb, the potential generator, i.e. the potential for the electric field
The "field generator" Co supplying ci is controlled to switch the polarity of the electric field, ie to generate an electric field of reversed polarity. In the case of a count value which does not reach the limit value, the electric field generator Co is controlled so that it continues to generate an electric field, ie generates a corresponding potential ci with the previous polarity. Also, if the result of the comparison corresponds to a loss of digits during the course of the pulse train being counted, the counter is immediately reset to zero;
That is, it indicates that the pulse train vb has not yet arrived at the detector Det.

The duration tx of the pause period p can therefore be particularly short, equal to or different from the transmission duration of the information inf, which in FIG. 1 was assumed to be approximately 500 ms. The shorter the pause period p is, the
The value of the control voltage ci at the electrode of the optical switch S is
In order to prevent its aging, it must be even higher. However, in the present invention, as known from the above-mentioned document (3), for example 500 ms in each case of one polarity and then in each case the other polarity.
Approximately the same value of polarity reversal with 500 ms is also applicable. That is, in the present invention, various types of operation methods are possible depending on the duration of the information transmission inf and the duration of the pause period p.

According to the embodiment of the present invention, even though the value of the optimal control potential or control voltage ci for the optical switch S is different during the information transmission period inf and during the rest period p, The additional problem is solved in that the control potential ci, which is individually set very accurately, can be used in a very advantageous manner for controlling the light switches S of the optical switches S. Furthermore, in this embodiment, at least one of the optical switches, if not the electric field generator Co, possibly the detector Det and the photoelectric converter Opt/El, which can be mounted on the same substrate, is The rate of non-defective products during manufacturing can be significantly increased in the following manner. In this embodiment, therefore, specific values ci within a wide permissible range of significantly different control voltage values ci can be used in each case precisely, rapidly and easily reproducibly. Therefore, in order to improve the non-defective product rate, in this embodiment, this kind of optical switch S and its control device Co, Det, Opt/El are additionally
Particularly economically advantageous possibilities are obtained for producing these for intensive use in switch frames of telephone exchange equipment.

According to this embodiment, this objective is achieved as follows. One or more electric field generators Co, which supply the electric field to the electrodes, convert the digital words stored in the memory, using a DA converter, into an analog potential c, which is applied to the electrodes and generates an electric field.
In particular, a D/A converter whose analog output voltage ci is stabilized against fluctuations in the DC voltage source in the electric field generator Co can be constructed in integrated technology, the analog output side of the converter being ,
The digital input side of this converter is electrically conductively connected to at least one electrode of the optical switch S to be controlled, and the digital input side of this converter is connected to
It has at least one memory and is connected to a byte generator which during operation generates words formed from the digits. The detector Det controls this memory in such a way that it is synchronized by a polarity switching command vb and generates a word corresponding to the polarity. Furthermore, a plurality of light switches are controlled by the only electric field generator Co of this kind via switches operated in a time-division multiplexed manner, each light switch S having its own specific Various control voltages ci are supplied. Literature mentioned at the beginning (1)
All configurations described in can also be used in the present invention.

Considering the degradation of the controlled optical switch S in the following way during the duration of a single information block inf of the optical signal (the embodiment shown in FIG. 1 has a duration of 500 ms): Control voltage or control potential
The respective optimal value of ci is generated more precisely. That is, we take into account the slight changes in the optimal value of the potential ci that occur during this duration.

In this way, the generated potential ci is thus varied during the duration of the information block in accordance with the optimum value change. Furthermore, for example, the characteristic curve of the DA converter and/or the respective digital word, which is supplied to this DA converter and which generates the analog potential ci in each case, can be transferred to an information block inf of the optical signal modulated by the subscriber information. can be varied continuously or in small jump changes, thus substantially continuously, during the transmission period of . For example, the word in question, which corresponds to the analog value ci, is substantially changed by changing its least significant digit, e.g. using an adder or a subtracter, in each case for the duration of the information block inf. Can be made larger or smaller continuously.

During the transmission of information blocks (inf in Figure 1)
The attenuation of the optical switch S is measured continuously in each case in its non-conducting cut-off transmission direction at any instant or at different instants in time, and the measurement results are used for adjustment, i.e. for changing the control voltage c. By using this, a particularly precise control voltage ci can be generated by the DA converter. This measurement can be carried out, for example, by means of a coupler or an optical receiver inserted in a branch of a connecting path which is not connected through the connecting path, and which determines the coupling strength of this branch in the connecting path from time to time, if not continuously. It is possible to measure and to use the coupling strength thus measured to vary the characteristic curve of the transducer and/or the respective generated digital word. In this case, the optical receiver can also be coupled directly to the respective optical switch S in the vicinity of the link L of the switch frame or to the associated switch frame output line LL.

As a result of the measurement results, the control computer of the switch frame can be systematically adjusted upwards and downwards through the characteristic curve of the DA converter and/or the respective controlling digital word to determine the respective optimal value of the control voltage c. It can be controlled to change until detected.

For this measurement it is also possible to use standardized measurement flash pulses which are inserted into specific time slots of the information block inf. This makes the measurements more accurate. In other words, regardless of the number of connections established through the connection path,
and is completely independent of the analog amplitude of the information transmitted during the connection, and virtually independent of the code used for the transmission.

In a corresponding manner, even during the rest period p, a high stability of the switching state of the light switch S is achieved even during the rest period p by means of a continuous change of the associated digital words and these digital words and/or the characteristic curve. It can be done.

The change in the characteristic curve of the DA converter is based on the digital word and
This corresponds to a change in the correspondence relationship with the analog output signal ci of the DA converter. Often it is better to change the digital word itself, in particular by multiplying it numerically by a factor corresponding to the transmission duration to pause duration ratio, in particular to generate a word controlling the pause duration from a word controlling the transmission, for example. However, it is relatively easy in terms of hardware, and is reliable and accurate.

During at least one part of the rest period p, at a predetermined control voltage ci, which depends on the type of light switch used, the same connection path is connected to this rest period p.
In principle, it can also be used in the same way for the additional transmission of additional information blocks inf, again with optimum attenuation values. The optimum value for the control voltage ci can be found, for example, in the above-mentioned documents (11), (13) and (21) Optic Letters 2 (February 1978).
It is clear from No. 2, pages 45 to 47. By not making feed-through connections for the remainder of the down period,
The remaining aging of the light switch can be removed.

In summary, the invention, including its embodiments, is suitable for switching systems using predominantly optical signals, in which the switching function is performed by a substrate having a matrix of optical switches.

In optical switches integrated on an electro-optical basis, aging phenomena, ie drifts due to carrier generation or carrier migration in particular in the substrate crystal, appear. This effect can be avoided by periodically switching the polarity of the control voltage, ie reversing its polarity.
However, during this polarity switch, the information flow in the connection path is interrupted. It is therefore advantageous to be able to adapt the transmission method to periodic polarity switching with little loss of information, and since optical regenerators are still problematic at present, PCM A transmission method is used in which pulse distortions in the information can be avoided and, moreover, the bit transmission rate can be easily adapted to developments.

Control of the optical switch is accomplished relatively simply by means of a substantially rectangular potential at a frequency of 2 Hz or more. Depending on the principle of the light switch, one of the light switches
One electrode or several electrodes are each applied with a positive or negative potential alternately, while the remaining electrodes are applied with, for example, a fixed earth potential or, for example, a rectangular potential of opposite polarity. In particular, the potential of the electrodes can also be reversed in a manner known per se in order to connect the connecting paths through each time at approximately the same value of the control voltage. In any case, the polarity is reversed regularly in the direction of the electric field of the electrode using an optical polarity switching command to eliminate aging. This polarity reversal can advantageously be controlled as follows. That is, a characteristic polarity switching command bit or a plurality of bit strings of this type are inserted into the optical information stream, for example, every 0.5S. By generating these bits, control is performed to invert the polarity of the potential. The polarity switching command is transmitted over the entire optical transmission section. The polarity reversal of the electric field can therefore be synchronized over the entire transmission path, independent of the respective length of the optical transmission line.

The optical transmitter of the transmission section e.g. does not transmit information for a short time interval, called a pause period, following the generation of the polarity change command bit. This rest period is then only used for reversing the polarity of the electric field. However, it is also possible to carry out transmission during the pause period. This pause period can be incorporated into the superframe structure of the switching system, along with transmission information and signaling such as dialing signals.

For the information in the entire transmission interval, a code, for example an HDB3 code, which does not normally contain relatively long strings of "0" or "1" digits, can be used. On the other hand, the polarity change command bit string forms, for example, a continuous string of "0" digits or "1" digits. This allows easy identification of this switching command bit in the detector. Before or within the switch frame, a portion of the incoming power of the optical signal is extracted, for example by means of a directional coupler, and processed in the control part of the exchange after optoelectronic conversion. That is, this control section acts so that when the polarity switching command bit or this bit string arrives, the polarity of the electric field in all the optical switches of the relevant connection path is simultaneously reversed. In a computer-controlled switching system, this is also possible if the computer is also able to perform the functions of a detector and also of an electric field generator, using connection plans stored in the computer. It is.

In order to avoid loss of subscriber information during idle periods and/or during the transmission of polarity-switching bits modulated into the optical signal, the subscriber information is compressed accordingly in time before transmission and is compressed after transmission. It can be expanded in time again. For example, this is the same as the transmission method described in (21) German Patent No. 1245438, (22) German Patent No. 1279768, or (23) German Patent Publication No. 2902897.5. It is done in a similar way.

The object of the embodiment of the invention just described is that the polarity switching command can easily be determined from the transmitted optical signal train by additional means that are easily realizable and require only a short duration. It means to remove or make it detectable. Further, the present invention
For the transmission of optical signals formed from digits and modulated by subscriber information, in order to detect polarity switching commands with little disturbance.
I want to be able to use any code instead of HDB3 code.

This object is achieved by the measures defined in claim 9, namely by using an extra-intense flash pulse of short light intensity as the polarity switching command.

In FIG. 2, a particularly large-amplitude, short-lasting polarity switching command vb is illustrated. This switching command has, for example, an amplitude 3 to 6 times that of the other transmitted optical signal inf. The duration of this polarity switching command vb, which is a flash pulse, is only 1 ns.

The polarity switching command vb is thus formed by a short flash pulse of this type, which has a light intensity significantly higher than the maximum light intensity of the optical signal inf modulated by the information. Due to the large amplitude of this particularly intense flash pulse, it can be easily detected and extracted as a flash pulse within the overall signal os (FIG. 3). Because of this easy detection, it is possible to detect information that is
No disadvantages arise if the light intensity is continuously zero during the duration of the transmission of inf. That is, the polarity switching command vb formed by the flash pulse is very easily detectable even if there is a disturbance during the transmission of the signal inf, even when the code of HDB3 is not used.

FIG. 2 illustrates an embodiment in which the flash pulse vb has two different amplitudes vb (i.e. vb' and vb''). In this way it is possible to use a flash pulse of one amplitude vb′ for one polarity switching direction and a flash of the other amplitude vb″ for the other polarity switching direction. Pulses can be used. In this way, when the duration of the individual polarity switching phases differs, e.g. depending on the Q of the attenuation in the non-through-connected direction of the optical switch S, from one polarity switching command to the next polarity switching command When the duration of the polarity is different, different polarity switching phases can be reliably controlled by the polarity switching command. This is also stated in claim 6. Moreover, in this way it is possible to adjust the optimal cut-off damping in the non-through-connected direction of the optical switch S by simply changing the duration of the polarity switching phase, without changing the characteristic curve of the DA converter. is possible.

In principle, however, it is also possible to characterize the polarity switching in one direction and the polarity switching in the other direction by differently configured polarity switching commands. If the polarity switching command is also formed by a short flash pulse of the same amplitude with a particularly high light intensity, the polarity switching command for polarity switching in one direction can also be modified for polarity switching in the other direction by e.g. It can be formed separately from the polarity switching command. i.e. the polarity switching command to initiate polarity switching in one direction is the only flash pulse of this kind.
vb and the polarity switching command which initiates the polarity switching in the other direction is formed in each case by two closely successive flash pulses of this type. In this case, to detect the polarity switching command,
The number of flash pulses, rather than the flash pulse amplitude, is evaluated. By the way, for evaluation, for example, the detector
For example, on the input side of the control device (third
(Fig.), a threshold circuit can be provided which responds to the flash pulse vb but not to the optical signal inf modulated by the information signal. The polarity switching command vb detected in this way can be separated from the other signals inf by a threshold circuit and supplied as a control command vb to the electric field generator Co for switching the polarity of the electric field. In FIG. 2, the threshold value sw of a threshold value circuit of this kind is illustrated in order to show that the control command vb can be formed, for example, by the amplitude of the flash pulse vb exceeding this threshold value sw. . That is, the amplitude of the switching command vb is, for example, (vb'-sw) or (vb''-sw).

The flash pulses vb can be easily generated by means of lasers which are especially provided for this purpose, the flash pulses vb being e.g. It is input coupled to the conductor track LL.

Typically, the polarity change command vb is followed by a relatively long pause period tx=p of at least, for example, 400 ns, if not 500 ms, until the next time slot for the signal os or inf. However, within the first part of the rest period p, for example 400 ns, the electric field is changed by the electric field generator Co for the time allowed to it tx=p and then is usually reversed in polarity for example 500 ms. There is even. However, as can be seen from FIG. 3, within the first part of this rest period p of 400 ns, additional control signals, for example measurements for the respective cut-off attenuation of the optical switch S, can be transmitted. Receiving element, e.g. detector Det
Since the diodes at are initially mostly overcontrolled by the flash pulse vb, a short recovery pause ep of, for example, 5 ns is inserted before the transmission of the signal.
This type of recovery pause is illustrated in Figure 2.
EP is flash pulse VB or additional flash pulse
If vb is also transmitted or supplied at the end of the 500 ms field polarity reversal pause p, then the signal
It can also be inserted before the first time slot of ihf.

[Brief explanation of drawings]

1 shows the time course of a block sequence of a modulated optical signal for explaining the method according to the invention; FIG. 2 shows a transmitted signal with a polarity switching command formed by a flash pulse; Figure 3 is a block diagram of a switch frame of a switching device in which the method of the invention can be implemented; FIG. 4 is a schematic diagram of a known optical switch. S...Optical switch or photoelectric coupling point, LL...Light conductor path or optical fiber, Co...Electric field generator or potential generator, Det...Detector, Opt/El
...Photoelectric converter, L...Link, OS...Optical signal,
vb...Polarity switching command, inf...Information signal, p...
Rest period, tx...rest duration, ep...recovery rest period, is...part of the energy of the optical signal, ci...
...Control potential or control voltage.

Claims (1)

[Scope of Claims] 1. A method for controlling an optoelectronic coupling point S of a switching device having a link L, which is an optical conductor path, for transmitting an optical signal os, wherein the coupling point S is manufactured in an integrated technology on a substrate. It forms a light switch S,
Moreover, the light switches each have at least two adjacent mutually parallel first and second light sections.
the first light section of the light section.
The light flow input into the light section of the optical switch is controlled by the control potential acting on the light section, that is, the light flow input into the first light section of the optical switch is controlled by the control potential acting on the light section.
along each optical section of the light guide path which is coupled into the optical section of the first optical section or is carried without coupling into the optical section of the first optical section and which is formed on the substrate in integrated technology. In each case, at least one electrically conductive electrode is designed as a control electrode of the light switch, which control electrode, by means of its control potential and thus the electric field, switches the light guided into the light path as required. , a control potential is applied to the optical path and one or more electric field generators Co supply appropriate control potentials to the relevant electrodes of the optical switch, and a polarity change command detector
Optoelectronic coupling of the type in which the one or more electric field generators Co controlled by Det and the polarity switching command detector Det switch the polarity of the electric field by means of the control potential acting on the light section concerned. In the method of controlling the point, the polarity of the electric field of at least some of the electrodes is modulated onto the respective optical signal os, and the duration tx of the pause period p of the information signal inf coming from the optical conductor LL is controlled. and at least the polarity of the electric field at all the connection points S of the connection paths to be formed, manufactured on the same substrate, according to the polarity switching command vb carried by modulation on the optical signal os. A method for controlling a photoelectric coupling point of a switching device, characterized in that the reversal is carried out in synchronization. 2. A part of the energy of the optical signal os is output-coupled from a connecting path formed by the connection, and a digit string vb having a special characteristic in the output-coupled energy is at least connected to the corresponding substrate KF on the corresponding substrate KF. the polarity switching command vb for synchronously inverting the polarity of the electric field of the electrode during the duration tx of the rest period p along the connection path, and transmitted modulated by the subscriber information inf; 2. The method according to claim 1, wherein the optical signal os is divided by the pause period p and transmitted block by block. 3. The subscriber information inf is digitized by HDB3 code before transmission, and the optical signal os is modulated and transmitted by the HDB3 coded signal, and the polarity switching command is the same. digit string
The digit string vb transmitted as vb immediately before the pause period p and output-coupled is compared with the output signal of a synchronously operating oscillator provided in the detector Det, and The result is counted in a counter of the detector Det, and when the counting result exceeds a threshold value, the electric field generator Co is controlled to change the polarity of the electric field.
That is, the electric field generator Co is controlled so that an electric field having an inverted polarity is generated, and when the counting result does not reach a threshold value, the electric field of the previous polarity is continued to be applied. The method described in section. 4 said one or more electric field generators Co applying said electric field to said electrodes are synchronized by said polarity switching command and stored in a memory each time during said rest period p as well as during a transmission period; A patent for converting a corresponding digital word using a DA converter into a corresponding analog electrical control voltage or potential, which analog voltage is applied to the electrodes to generate a correctly polarized electric field with the correct strength in each case. A method according to any one of claims 1 to 3. 5. the characteristic curve of said DA converter and/or the respective generated digital word being varied substantially continuously during the transmission of said block of said optical signal modulated by said subscriber information inf; The method according to claim 4. 6. Measuring the degree of undesired optical coupling in the connection path where the connection should not be formed, using at least one optical receiver coupled to the branch path where the connection should not be formed, of the connection path to be formed; 6. The method as claimed in claim 5, wherein the measured degree of coupling is used to modify the characteristic curve of the DA converter and/or the respective generated digital word. 7. The stored digital words converted during the transmission of the optical signal are different from the stored digital words converted during the pause period p. The method according to any one of paragraph 6. 8. During the pause period p or at least a part of the pause period p, the optical signals inf, os are
8. The method as claimed in claim 1, wherein the transmission is carried out via the same connection that was established during the transmission. 9 A method for controlling an optoelectronic coupling point S of a switching device having a link L, which is an optical conductor path, for transmitting an optical signal os, the coupling point S having an optical switch S manufactured in integrated technology on a substrate. has formed,
Moreover, the light switches each have at least two adjacent mutually parallel first and second light sections.
the first light section of the light section.
The light flow input into the light section is controlled by the control potential acting on the light section, i.e. the light flow input into the first light section of the optical switch is coupled into the second light section. at least one electrically conductive conductor in each case along each optical section of the optical conductor track which is held in the first optical section without coupling or in-coupled and which is formed on the substrate in integrated technology. An electrode is formed as a control electrode of the light switch, which control electrode, by means of a control potential and thus an electric field, controls the light guided into the light section as required by means of the electrical control potential of the electrode. In order to switch, a control potential is applied to the optical path and 1
one or more electric field generators Co supply appropriate control potentials to the relevant electrodes of the optical switch, and the polarity change command detector Det and the polarity change command detector
A method for controlling a photoelectric coupling point of the type in which the one or more electric field generators Co controlled by Det switch the polarity of the electric field of the control potential acting on the optical section in question, the polarity of the electric field of the electrode is reversed during the duration tx of the pause period p of the information signal inf coming from the light guide LL, modulated onto the respective light signal os, and at least identical The polarities of the electric fields at all the connection points S of the connection paths to be formed on the substrate are synchronized and reversed by a polarity switching command vb modulated on the optical signal os. , and a method for controlling a photoelectric coupling point of a conversion device, characterized in that the polarity switching command vb is formed by a short flash pulse having a light intensity significantly greater than the maximum light intensity of the optical signal os. 10 Flash pulse for polarity reversal in one direction
11. The method according to claim 9, wherein vb has a different amplitude vb' from the amplitude vb'' of the flash pulse vb for polarity reversal in the other direction. 11. 11. A method according to claim 9 or claim 10, followed by a recovery pause period ep during which the modulated optical signal os is not transmitted. 12. The flash pulse vb is generated by a special laser and the switch frame is Claim 9 for input coupling to the relevant connecting light guide path LL
10. The method according to any one of paragraphs 10 and 11. 13 The detector Det forming the input side of the control device of the exchange responds to the flash pulse vb but not to the optical signal os modulated by the information inf, thereby issuing the polarity switching command. Vb′,
Separate vb'' from other signals inf and control command vb
10. The method according to claim 9, further comprising a threshold circuit for controlling said electric field generator Co such that polarity reversal of said electric field is effected.