Photonic system with a photonic integrated circuit and method for operating a photonic system with a photonic integrated circuit

Abstract

The present invention relates to a photonic system (1) comprising: a photonic integrated circuit (PIC) comprising a first electro-optical modulator (EOM, EOM1, EOM11) and a second electro-optical modulator (EOM, EOMn, EOM1m); a first driver (5) for providing a control voltage for the first or the second electro-optical modulator (EOM, EOM1, EOMn, EOM11, EOM1m); a first switch (S1, S11), wherein the first electro-optical modulator (EOM, EOM1, EOM11) is connectable to the first driver (5) via the first switch (S1, S11); and a second switch (Sn, S1m), wherein the second electro-optical modulator (EOM, EOMn, EOM1m) is connectable to the first driver (5) via the second switch (Sn, S1m).The invention further relates to a method for operating a photonic system (1) with a photonic integrated circuit (PIC) comprising a first and a second electro-optical modulator (EOM, EOM1, EOMn, EOM11, EOM1m), and with a first driver (5) for providing a control voltage for the first and second electro-optical modulator (EOM, EOM1, EOMn, EOM11, EOM1m), wherein the first driver (5) generates a first control voltage in a first control step and this is provided to the first electro-optical modulator (EOM, EOM1, EOM11) via a first switch (S1, S11), and wherein the first driver (5) generates a second control voltage in a second control step following the first control step and this is provided to the second electro-optical modulator (EOM, EOMn, EOM1m) via a second switch (Sn, S1m). The invention further comprises a control unit (4) which, by means of information in an internal memory (6), enables a time-synchronous control of the drivers (5, 5') via the DAC function (7, 7'), as well as of the switches (S) with periodic repetition.

Description

[0001] The present invention relates to a photonic system comprising a photonic integrated circuit (PIC) comprising a first electro-optical modulator and a second electro-optical modulator (EOM). Furthermore, the invention relates to a method for operating a photonic integrated circuit comprising a first electro-optical modulator and a second electro-optical modulator.

[0002] Such photonic systems find applications in network technology, quantum computers, and quantum cryptography, among others. The photonic integrated circuits of these systems typically contain waveguides and active optical elements such as electro-optical modulators (EOMs), as well as Mach-Zehnder interferometers, which consist of waveguides, beam splitters, and EOMs. The electro-optical modulators enable the refractive index of the waveguide material to be changed. For example, it is possible to influence this change by applying an electrical voltage, also referred to below as the control voltage.

[0003] The performance of such photonic integrated circuits typically scales with the number of electro-optical modulators. As the number of electro-optical modulators increases, so does the number of supply lines and analog driver circuits required for control, referred to below as drivers. This complicates the scaling of high-performance photonic integrated circuits in the aforementioned application areas. In particular, the economic integration of such photonic integrated circuits on printed circuit boards (PCBs) is limited.

[0004] Against this background, the task arises to facilitate the realization of high-performance photonic systems with an increased number of electro-optical modulators.

[0005] To solve the problem, a photonic system is proposed, comprising: a photonic integrated circuit, PIC, comprising a first electro-optical modulator and a second electro-optical modulator, EOM; a first driver for providing a control voltage for the first or second electro-optical modulator; a first switch, wherein the first electro-optical modulator is connectable to the first driver via the first switch; and a second switch, wherein the second electro-optical modulator is connectable to the first driver via the second switch.

[0006] In the photonic system according to the invention, several electro-optical modulators can be selectively connected to the first driver via the switches to be controlled by the first driver. This makes it possible to use the first driver sequentially to control several electro-optical modulators. This allows the number of required drivers of the photonic system, as well as the supply lines leading to these drivers, to be reduced. Consequently, the realization of high-performance photonic systems with a larger number of electro-optical modulators is facilitated.

[0007] Although the invention is explained with reference to a first and a second electro-optical modulator, the photonic integrated circuit preferably comprises more than two electro-optical modulators. Particularly preferably, the photonic integrated circuit comprises more than 10, for example, more than 100, in particular more than 1000 electro-optical modulators.

[0008] The photonic integrated circuit preferably comprises at least one, preferably several, waveguides coupled to the first and / or second electro-optical modulator. The waveguides can be formed, for example, from Si, SiN, SiON, GaAs, LiNbO3 (LN), or LiTaO3 (LT). The waveguides are preferably formed on a substrate of the photonic integrated circuit, for example, a Si substrate or an SiO2 substrate.

[0009] The electro-optical modulators are preferably designed to enable a change in the refractive index of a waveguide as a function of an electric field in the waveguide material or as a function of an electrical voltage drop across the waveguide material. For example, the electro-optical modulators can have an electrode to which the control voltage provided by the driver is applied relative to a substrate of the photonic integrated circuit. Alternatively, the electro-optical modulators can have two electrodes between which the control voltage provided by the driver is applied.

[0010] The electro-optical modulators can be designed as phase-shift modulators or as part of a Mach-Zehnder interferometer. The electro-optical modulators can thus be used to adjust the phase and / or amplitude of optical modes.

[0011] The switches of the photonic system can be set to an electrically conductive state and an electrically non-conductive or high-impedance state. If the switches of the photonic system are in the electrically conductive state, the electro-optical modulator is referred to below as being connected to the respective driver via the switch, since in this state an electrically conductive connection exists via the switch.

[0012] According to an advantageous embodiment of the invention, the photonic system comprises a control unit for controlling the first driver and the first and second switches, wherein the control unit is configured, in a first control step, to control the first and second switches such that the first driver is connected to the first electro-optical modulator and to control the first driver such that the first driver generates a first control voltage for the first electro-optical modulator; and, in a second control step following the first control step, to control the first and second switches such that the first driver is connected to the second electro-optical modulator and to control the first driver such that the first driver generates a second control voltage for the second electro-optical modulator.Through such control, the first and second electro-optical modulators can be controlled by the same driver, eliminating the need to provide a separate driver of the photonic system for each of the electro-optical modulators. Control occurs sequentially, so that only one electro-optical modulator is connected to the driver at a time and supplied with a control voltage by it. The electro-optical modulators can maintain their state, determined by the respective control voltage, for a limited period even when they are not connected to the driver, for example, by storing an electrical charge through an internal capacitance of the electro-optical modulator.Preferably, the photonic system comprises more than two electro-optical switches, and the control unit is configured to connect these further electro-optical modulators to the first driver via further switches in further control steps following the second control step, and to control the first driver such that the first driver generates a further control voltage for the respective further electro-optical modulator. While these further electro-optical modulators are being controlled by the driver, the first and second electro-optical modulators, among others, are not connected to the first driver and are not controlled by a control voltage. During this period, the first and second electro-optical modulators, as well as any further electro-optical modulators not connected to the driver, must maintain their state predetermined by the respective control voltage.

[0013] According to an advantageous embodiment of the invention, the photonic system comprises a second driver for providing a control voltage for an electro-optical modulator; a third electro-optical modulator and a third switch, wherein the third electro-optical modulator is connectable to the second driver via the third switch; and a fourth electro-optical modulator and a fourth switch, wherein the fourth electro-optical modulator is connectable to the second driver via the fourth switch. Such an embodiment enables a reduction in the number of required drivers while simultaneously controlling multiple electro-optical modulators. In this respect, groups of electro-optical modulators are formed, each of which can be controlled via a common driver.This makes it possible to provide a photonic system design that represents a compromise between the highest possible number of electro-optical modulators, thus the highest possible system performance, and the smallest possible number of analog circuits, thus the lowest possible area and energy requirements. Preferably, the photonic system comprises more than two drivers and additional electro-optical modulators, wherein these additional drivers can each be connected to the additional electro-optical modulators via additional switches.

[0014] In this context, an embodiment of the invention has proven particularly advantageous in which the photonic system comprises a control unit for controlling the first and second drivers as well as the first, second, third and fourth switches, wherein the control unit is configured, in a first control step, to control the first and second switches such that the first driver is connected to the first electro-optical modulator and to control the first driver such that the first driver generates a first control voltage for the first electro-optical modulator; and, in a second control step following the first control step, to control the first and second switches such that the first driver is connected to the second electro-optical modulator and to control the first driver such that the first driver generates a second control voltage for the second electro-optical modulator,In a third control step, the third and fourth switches are controlled such that the second driver is connected to the third electro-optical modulator, and the second driver is controlled such that the second driver generates a third control voltage for the third electro-optical modulator; and in a fourth control step following the third control step, the third and fourth switches are controlled such that the second driver is connected to the fourth electro-optical modulator, and the second driver is controlled such that the second driver generates a fourth control voltage for the fourth electro-optical modulator. The first and second, as well as the third and fourth, electro-optical modulators are controlled sequentially, but preferably such that the first electro-optical modulator is then controlled by the first driver.when the third electro-optical modulator is controlled by the second driver. Preferably, the second electro-optical modulator is controlled by the first driver when the fourth electro-optical modulator is controlled by the second driver. Thus, an optical system can be implemented with a small number of drivers, which are used in parallel to control different electro-optical modulators. In this respect, the first and third control steps preferably occur simultaneously, and the second and fourth control steps occur simultaneously.

[0015] According to an advantageous embodiment of the invention, the photonic system comprises a first group switch connected to the first switch and to the second switch, wherein the first electro-optical modulator is connectable to the first driver via the first switch and the first group switch, wherein the second electro-optical modulator is connectable to the first driver via the second switch and the first group switch. Such an embodiment offers the advantage that a group of electro-optical modulators can be selected via the first group switch, from which group a single electro-optical modulator is selected by the first or second switch. In this respect, hierarchical addressing of electro-optical modulators is enabled.In such a design, the electro-optical modulators can be indirectly connected to the driver via the switch, since the group switch is additionally arranged between the respective switches and the driver.

[0016] According to an advantageous embodiment of the invention, the photonic system comprises a control unit for controlling the first driver and the first and second switches as well as the first group switch, wherein the control unit is configured, in a first control step, to control the first and second switches as well as the first group switch such that the first driver is connected to the first electro-optical modulator and to control the first driver such that the first driver generates a first control voltage for the first electro-optical modulator; and, in a second control step following the first control step, to control the first and second switches as well as the first group switch such that the first driver is connected to the second electro-optical modulator and to control the first driver such thatthat the first driver generates a second control voltage for the second electro-optical modulator. Thus, through such control, the first and second electro-optical modulators can be controlled by the same driver, eliminating the need to maintain a driver of the photonic system for each of the electro-optical modulators. The control occurs sequentially, so that only one electro-optical modulator is connected to the driver at a time and is supplied with a control voltage by it. The electro-optical modulators can maintain their state, determined by the respective control voltage, for a limited period of time even when they are not connected to the driver.For example, by storing an electrical charge through an internal capacitance of the electro-optical modulator. Preferably, the photonic system comprises more than two electro-optical modulators, and the control unit is configured to connect these additional electro-optical modulators to the first driver via additional switches in subsequent control steps following the second control step, and to control the first driver such that the first driver generates an additional control voltage for the respective additional electro-optical modulator. While these additional electro-optical modulators are controlled by the driver, the first and second electro-optical modulators, among others, are not connected to the first driver and are not controlled with a control voltage.

[0017] According to an advantageous embodiment of the invention, the photonic system comprises a fifth electro-optical modulator, a fifth switch, a sixth electro-optical modulator, a sixth switch, and a second group switch connected to the fifth switch and the sixth switch, wherein the fifth electro-optical modulator is connectable to the first driver via the fifth switch and the second group switch; and wherein the sixth electro-optical modulator is connectable to the first driver via the sixth switch and the second group switch. Such an embodiment offers the advantage that several groups of electro-optical modulators can be controlled by the same driver. The groups can be designed, for example, as rows of a matrix or as columns of a matrix of electro-optical modulators. In this case, a row orA column of the matrix can be selected. The selection of an individual electro-optical modulator within the row or column can then be made using the first, second, fifth, or sixth switch.

[0018] According to an advantageous embodiment of the invention, it is provided that the control unit is further configured to control the second group switch and is set up to control the fifth and sixth switches as well as the second group switch in a third control step such that the first driver is connected to the fifth electro-optical modulator and to control the first driver such that the first driver generates a fifth control voltage for the fifth electro-optical modulator; and in a fourth control step following the third control step, to control the fifth and sixth switches as well as the second group switch in such a way that the first driver is connected to the sixth electro-optical modulator and to control the first driver such that the first driver generates a sixth control voltage for the sixth electro-optical modulator.It is preferably provided that the third control step follows the first and second control step, ie that the control of an electro-optical modulator via the second group switch only takes place when the control of the electro-optical modulators via the first group switch has been completed.

[0019] According to an advantageous embodiment of the invention, the control unit has a memory for storing control information for the first driver and, if applicable, the second driver and the switches and, if applicable, group switches. The control information comprises, in particular, control information for the drivers of the photonic system and control information for the switches and, if applicable, group switches. For example, to control an electro-optical modulator, control information for the respective driver, in particular an analog voltage at the driver, is required on the one hand, and control information for the switches on the other hand, so that the control voltage provided by the driver can be switched through to the respective electro-optical modulator.

[0020] According to an advantageous embodiment of the invention, the control unit comprises a processor, wherein the control information in the memory comprises instructions executable by the processor. The instructions can be executed in parallel and sequentially to enable control of the drivers and switches, as well as group switches if necessary. Such an embodiment does not require the control information to be stored as concrete numerical values, but rather allows the control information to be generated, for example, based on a calculation rule, for example in real time.

[0021] According to an advantageous embodiment of the invention, the photonic system comprises a first support capacitance, in particular a first capacitor or a dedicated first parasitic capacitance, arranged in parallel with the first electro-optical modulator; and a second support capacitance, in particular a second capacitor or a dedicated second parasitic capacitance, arranged in parallel with the second electro-optical modulator. The support capacitance can improve the ability of the respective electro-optical modulator to hold the applied control voltage even when the modulator is no longer connected to the respective driver. In this respect, the total capacitance of the respective electro-optical modulator formed by the internal capacitance of the electro-optical modulator and the support capacitance can be increased.Preferably, the first support capacitance and the second support capacitance are dimensioned such that a control voltage applied to the first or second electro-optical modulator can be maintained over a predetermined cycle duration at least to 95%, preferably at least to 97%, particularly preferably at least to 98%, for example at least to 99%.

[0022] According to an advantageous embodiment of the invention, the photonic integrated circuit comprises the first and second support capacitances. Preferably, all support capacitances are formed as part of the photonic integrated circuit, parallel to the electro-optical modulators of the photonic integrated circuit. Providing the support capacitances as part of the photonic integrated circuit enables a compact design.

[0023] According to an advantageous embodiment of the invention, the photonic integrated circuit comprises the first and second switches. Preferably, all switches provided for connecting the electro-optical modulators of the photonic integrated circuit to a driver are formed as part of the photonic integrated circuit. Providing the switches as part of the photonic integrated circuit enables a compact design.

[0024] According to an advantageous embodiment of the invention, the first switch and the second switch are transistors, in particular field-effect transistors (FETs). Preferably, all switches provided for connecting the electro-optical modulators of the photonic integrated circuit to a driver are designed as transistors, in particular as field-effect transistors.

[0025] According to an advantageous embodiment of the invention, the photonic integrated circuit comprises the first driver and, if appropriate, the second driver. Preferably, all drivers provided for providing a control voltage for the electro-optical modulators of the photonic integrated circuit are provided as part of the photonic integrated circuit.

[0026] Preferably, the drivers of the photonic system, for example, the first and possibly the second driver, are designed as drivers for symmetrical signal transmission. Such a design is particularly advantageous when the electro-optical modulators have two electrodes, e.g., two electrodes between which a waveguide is arranged.

[0027] Alternatively, the drivers of the photonic system, for example, the first and possibly the second driver, can be designed as drivers for asymmetric signal transmission. Such a design can be advantageous if the electro-optical modulators have an electrode to which a voltage is applied against the substrate, e.g., to adjust an electric field in a waveguide arranged between the electrode and the substrate.

[0028] A preferred embodiment is one in which the driver(s) of the photonic system, for example, the first driver and possibly the second driver, are each connected to the control unit via a digital-to-analog converter. Particularly preferably, the control unit is configured such that it controls the one or more digital-to-analog converters for generating the respective control voltage by the driver synchronously with the switches and, if applicable, group switches.

[0029] To achieve the object mentioned above, a method for operating a photonic system with a photonic integrated circuit is also proposed, which comprises a first and a second electro-optical modulator, as well as with a first driver for providing a control voltage for the first and second electro-optical modulator, wherein the first driver generates a first control voltage in a first control step and this is provided to the first electro-optical modulator via a first switch, and wherein the first driver generates a second control voltage in a second control step following the first control step and this is provided to the second electro-optical modulator via a second switch.

[0030] The method according to the invention can achieve the same advantages and technical effects as have already been described in connection with the photonic system according to the invention.

[0031] According to an advantageous embodiment of the invention, the first and second control steps are each repeated after a predetermined cycle duration has elapsed. Preferably, several, in particular all, electro-optical modulators of the photonic integrated circuit are each controlled once within the predetermined cycle duration. Thus, several, in particular all, electro-optical modulators of the photonic integrated circuit can be set to a predetermined state within the cycle duration. Within the subsequent cycle duration, this state can then be refreshed by controlling the electro-optical modulators in a manner identical to that used during the previous cycle duration. Alternatively, the state of the electro-optical modulators can be changed by controlling them with control voltages that differ from the previous cycle duration.

[0032] Alternatively or in addition to the advantageous embodiments explained above, the advantageous embodiments and features explained in connection with the device according to the invention can be used in the method.

[0033] Further details and advantages of the invention will be explained below with reference to the exemplary embodiments shown in the figures. Herein: Fig. 1 an exemplary photonic integrated circuit in a schematic representation; Fig. 2 an exemplary electro-optical modulator in a schematic representation; Fig. 3 a photonic system according to the state of the art; Fig. 4 shows a first embodiment of a photonic system according to the invention; Fig. 5 a representation of possible voltage curves during operation of the photonic system from Fig. 4; Fig. 6 shows a second embodiment of a photonic system according to the invention; Fig. 7 shows a third embodiment of a photonic system according to the invention; Fig. 8 shows a fourth embodiment of a photonic system according to the invention; and Fig. 9 a fifth embodiment of a photonic system according to the invention.

[0034] In the following, the terms “first”, “second”, etc., with regard to the described elements, for example switches or electro-optical modulators, do not serve to define a particular order of precedence, but merely to distinguish these elements from one another.

[0035] The schematic representation in Fig. Figure 1 shows an exemplary photonic integrated circuit (PIC). The photonic integrated circuit (PIC) is powered by one or more light sources (not shown), for example, a laser (see thick arrow in Fig. 1. The photonic input states or modes are guided in waveguides 2 of the photonic integrated circuit PIC and modulated by several electro-optical modulators EOM. The photonic integrated circuit PIC comprises several electro-optical modulators EOM, via which the phase of the respective mode can be influenced. In addition, several Mach-Zehnder interferometers MZI are provided as part of the photonic integrated circuit PIC, via which the amplitude of the modes can be influenced. The Mach-Zehnder interferometers MZI, for example, each use an electro-optical modulator EOM. In the Mach-Zehnder interferometer MZI, the light is split into two paths. While the phase in the first path is modulated by an electro-optical modulator EOM, no such modulation takes place in the second path. This results in phase-shifted modes that are then superimposed.Due to mode interference, the amplitude of the light emerging from the Mach-Zehnder interferometer (MZI) is modulated. According to a modification of the method described in . Fig. In the embodiment shown in Figure 1, EOMs are arranged in both paths of the MZl. In this case, the light is phase-shifted in both paths, with a positive and negative phase shift typically generated by corresponding voltage levels.

[0036] At the exit of the Fig. In the photonic integrated circuit PIC shown in Figure 1, a detector 3 for detecting photons is arranged on each waveguide 2. These detectors 3 can convert the optically processed signals in the photonic integrated circuit PIC into electrical signals.

[0037] The Fig. Figure 2 shows a detailed view of a Mach-Zehnder interferometer MZI. The Mach-Zehnder interferometer MZI comprises two waveguides 2 and an electro-optical modulator EOM. The electro-optical modulator EOM is designed here as an electro-optical modulator EOM with an electrode to which a control voltage is applied to the substrate of the photonic integrated circuit PIC, which is at ground potential (GND). A driver 5 is provided to control the EOM, which is preferably located externally of the photonic integrated circuit PIC. An electrical signal VS can be applied to the driver 5, for example, by a control unit. The electrical signal VS is amplified by the driver 5 and converted into a control signal suitable for controlling the electro-optical modulator EOM. In the present case, the driver 5 is designed as a driver for asymmetric signal transmission (AS).single-ended transmission).

[0038] In the Fig. Figure 3 shows a photonic system 1 according to the prior art. The photonic system 1 comprises a photonic integrated circuit PIC with several, here n, electro-optical modulators EOM. For each of these electro-optical modulators EOM, an electrical connection 3 is provided on the photonic integrated circuit PIC. External to the photonic integrated circuit PIC, a total of n drivers 5 are provided for controlling the n electro-optical modulators EOM. Control signals for the electro-optical modulators EOM of the photonic integrated circuit PIC can be provided via these drivers 5. Such a photonic system 1 requires a relatively large amount of space for the components and supply lines.

[0039] The representation in Fig. 4 shows a first embodiment of a photonic system 1 according to the invention with a photonic integrated circuit PIC comprising a plurality of electro-optical modulators EOM. For reasons of clarity, only a first electro-optical modulator EOM1 and a second electro-optical modulator EOMn are shown out of a total of n electro-optical modulators. The electro-optical modulators EOM1, EOMn are shown as capacitors, since the electro-optical modulators EOM1, EOMn according to this embodiment each comprise an electrode to which a control voltage is applied relative to the substrate. In this respect, the electro-optical modulators EOM1, EOMn each resemble a capacitor relative to the substrate.In parallel to the electro-optical modulators EOM1, EOMn, a supporting capacitance 10 is provided, which increases the total capacitance as a parallel connection of electro-optical modulator EOM1, EOMn and supporting capacitance 10 and thus contributes to the level of the control voltage applied to the respective electro-optical modulator EOM1, EOMn being able to be maintained over a longer period of time without the need to reapply the control voltage.

[0040] The photonic system further comprises a driver 5 for providing such a control voltage for the first or second electro-optical modulator EOM1, EOMn. Between the driver 5 and each electro-optical modulator EOM1, EOMn, a switch S1, Sn is provided, which is preferably configured as part of the PIC, i.e., formed on the substrate of the PIC. The switches S1, Sn can be configured, for example, as transistors, in particular field-effect transistors. Via the switches S1, Sn, an electro-optical modulator EOM1, EOMn can be selectively connected to the driver 5.

[0041] In Fig. 5 is a possible curve of the input signal VS of the driver 5 as well as the switching signals Vn, V1 over time t of the Fig. 4. Within a cycle T, all n electro-optical modulators EOM1, EOMn of the PIC are each controlled once, ie, connected once to the driver 5. After the cycle T, the control sequence is repeated to refresh the electro-optical modulators EOM1, EOMn or to control them with a modified control signal. The driver 5 generates an output signal depending on the input signal VS, which is forwarded via the switches S1, Sn to the respective electro-optical modulator EOM1, EOMn. Fig. 5 shows an example of the voltage applied to the switches S1, Sn in Fig. 4 applied switching signals V1 and Vn. It can be seen that the first electro-optical modulator EOM1 is always activated first within a cycle T, and the second electro-optical modulator EOMn is always activated last. While a switch S1, Sn is closed (as electrically conductive), the respective electro-optical modulator EOM1, EOMn is electrically connected to the output of driver 5, so that driver 5 can influence the potential at the electrode of the electro-optical modulator EOM1, EOMn.

[0042] The representation in Fig. 6 shows a second embodiment of a photonic system 1 according to the invention with a photonic integrated circuit PIC comprising n electro-optical modulators EOM. In contrast to the first embodiment, in the photonic system 1 according to the second embodiment, a total of two drivers 5, 5' are provided for controlling all electro-optical modulators EOM of the PIC, so that n-2 drivers can be saved compared to the prior art. Some of the electro-optical modulators EOM can be connected to the first driver 5 via a switch S assigned to the respective electro-optical modulator EOM. Another part of the electro-optical modulators EOM can be connected to the second driver 5' via a switch S assigned to the respective electro-optical modulator EOM.

[0043] For example, each of the drivers 5, 5' can drive n / 2 electro-optical modulators EOM. Optionally, more than two drivers 5, 5' can be provided to drive the n electro-optical modulators EOM of the photonic integrated circuit PIC.

[0044] The representation in Fig. 7 shows a third embodiment of a photonic system 1 according to the invention with a photonic integrated circuit PIC comprising n*m electro-optical modulators EOM. For reasons of clarity, of the total of n electro-optical modulators, only a first electro-optical modulator EOM11, a second electro-optical modulator EOM1m, a third electro-optical modulator EOMn1, and a fourth electro-optical modulator EOMnm are shown. The electro-optical modulators EOM11, EOM1m, EOMn1, EOMnm are shown here as capacitors, since according to this embodiment they each comprise an electrode to which a control voltage is applied relative to the substrate. In this respect, the electro-optical modulators EOM11, EOM1m, EOMn1, EOMnm each resemble a capacitor relative to the substrate.

[0045] The electro-optical modulators are divided into n groups G1, Gn, for example, in rows. Furthermore, in addition to the switches S11, S1m, Sn1, Snm, which are each assigned to an electro-optical modulator EOM11, EOM1m, EOMn1, EOMnm, group switches SG1, SGn are provided. These group switches are arranged between the first-mentioned switches S11, S1m, Sn1, Snm and the driver 5. In this respect, the group switches SG1, SGn are arranged in series with the parallel switches S11, S1m, Sn1, Snm. The first electro-optical modulator EOM11 can be connected to the driver 5, for example, via the first switch S11 and the first group switch SG1, and the second electro-optical modulator EOM1m can be connected to the driver 5 via the second switch S1m and the first group switch SG1.Furthermore, the third electro-optical modulator EOMn1 is connectable to the driver 5 via the third switch Sn1 and the second group switch SGn, and the fourth electro-optical modulator EOMnm is connectable to the driver 5 via the fourth switch Snm and the second group switch SGn.

[0046] The Fig. Figure 8 shows a fourth embodiment of a photonic system 1 according to the invention with a photonic integrated circuit PIC comprising n*m electro-optical modulators EOM. The electro-optical modulators EOM are arranged, at least logically, in n rows and m columns. This means that the n rows can each be selected via a group switch SG1, SGn, and the selection within a row is made by another switch assigned to the respective electro-optical modulator EOM. These switches are controlled, for example, via the switching signals V11 and Vnm.

[0047] The Fig. The topologies for controlling the EOMs shown in Figures 4 to 8 merely illustrate possible implementation forms for the number and cascading of drivers 5 and switches for controlling multiple electro-optical modulators (EOMs), in particular an EOM array. Further embodiments for other configurations of PICs and other applications of electro-optical modulators (EOMs) are conceivable, which can be realized by adapting the multiplexing method shown here.

[0048] The Fig.9 shows, based on a further embodiment of a photonic system 1 according to the invention, a circuit of the photonic integrated circuit PIC and the driver 5, which can also be used in the previously described embodiments. The photonic system 1 comprises a control unit 4 for controlling the switches S and the driver 5. Another component of the photonic system 1 is a digital-to-analog converter 7, which is provided between the control unit 4 and the driver 5. The digital-to-analog converter can convert a digital value provided by the control unit 4 into an analog voltage. This voltage can then be brought by the driver 5 to the voltage level required for the electro-optical modulators EOM.

[0049] A control unit 20, for example a computer system, is provided externally to the photonic system 1. This control unit 20 forwards control information to the control unit 4. The control unit 4 can store this information, for example, in an internal memory 6. The control information can include, for example, the control voltages for the electro-optical modulators EOM of the photonic integrated circuit PIC. The control unit 4 can be designed separately from the photonic integrated circuit PIC, for example, as a microcontroller or FPGA. Alternatively, it is possible for the control unit 4 to be designed as part of the photonic integrated circuit PIC. The control unit 4 can read the control information from the memory 6 and send it in a synchronized manner to the electro-optical modulators EOM via the digital-to-analog converter 7, the driver 5, and the switches.Preferably, within a cycle T, for n electro-optical modulators EOM, the voltage level for one electro-optical modulator EOM is applied for a duration T / n, and the corresponding switch S is switched through to the electro-optical modulator EOM. All other switches S are blocked during this interval and thus have a high impedance. This means that during a transition to the next electro-optical modulator EOM, the currently active switch S is switched off, the voltage for the next electro-optical modulator EOM is applied to the digital-to-analog converter 7, and the switch S for the next electro-optical modulator EOM is switched on. Thus, all electro-optical modulators EOMs controlled by driver 5 receive a control voltage refresh signal in each cycle T.

[0050] If the states of one or more electro-optical modulators need to be changed, another area of memory 6 can be accessed and read, which contains the respective new voltage values for all electro-optical modulators (EOM). Alternatively, the new voltage values can be generated by a calculation rule that can be executed in real time. The maximum frequency with which the electro-optical modulators (EOM) can be reprogrammed is determined by the cycle time T. Reference symbol: 1 photonic system 2 waveguides 3 Connection 4 Control unit 5.5' driver 6 storage 10 support capacity EOM electro-optical modulator EOM1 electro-optical modulator EOM11 electro-optical modulator EOM1m electro-optical modulator EOMn electro-optical modulator EOMn1 electro-optical modulator EOMnm electro-optical modulator PIC photonic integrated circuit G1 Group Gn Group S switch S1, S2 switch S11, S1m switch Sn1, Snm switch SG1, SGn group switches t time T cycle V1 switching signal Vn switching signal VS input signal of the driver

Claims

[1] Photonic system (1), comprising: a photonic integrated circuit (PIC) comprising a first electro-optical modulator (EOM, EOM1, EOM11) and a second electro-optical modulator (EOM, EOMn, EOM1m); a first driver (5) for providing a control voltage for the first or the second electro-optical modulator (EOM, EOM1, EOMn, EOM11, EOM 1m); a first switch (S1, S11), wherein the first electro-optical modulator (EOM, EOM1, EOM11) is connectable to the first driver (5) via the first switch (S1, S11); and a second switch (Sn, S1m), wherein the second electro-optical modulator (EOM, EOMn, EOM1m) is connectable to the first driver (5) via the second switch (Sn, S1m). [2] Photonic system (1) according to claim 1, characterized by a control unit (4) for controlling the first driver (5) and the first and second switches (S, S1, S11, Sn, S1m), wherein the control unit (4) is arranged to in a first control step, to control the first and second switches (S, S1, S11, Sn, S1m) such that the first driver (5) is connected to the first electro-optical modulator (EOM, EOM1, EOM11) and to control the first driver (5) such that the first driver (5) generates a first control voltage for the first electro-optical modulator (EOM, EOM1, EOM11); and in a second control step following the first control step, to control the first and second switches (S, S1, S11, Sn, S1m) such that the first driver (5) is connected to the second electro-optical modulator (EOM, EOMn, EOM1m) and to control the first driver (5) such that the first driver (5) generates a second control voltage for the second electro-optical modulator (EOM, EOMn, EOM1m). [3] Photonic system (1) according to claim 1, characterized by a second driver (5') for providing a control voltage for an electro-optical modulator (EOM); a third electro-optical modulator (EOM) and a third switch (S), wherein the third electro-optical modulator (EOM) is connectable to the second driver (5') via the third switch (S); and a fourth electro-optical modulator (EOM) and a fourth switch (S), wherein the fourth electro-optical modulator (EOM) is connectable to the second driver (5') via the fourth switch (S). [4] Photonic system (1) according to claim 3, characterized by a control unit (4) for controlling the first and second drivers (5, 5') and the first, second, third and fourth switches (S), wherein the control unit (4) is arranged to in a first control step, to control the first and second switches (S) such that the first driver (5) is connected to the first electro-optical modulator (EOM) and to control the first driver (5) such that the first driver (5) generates a first control voltage for the first electro-optical modulator (EOM); and in a second control step following the first control step, to control the first and second switches (S) such that the first driver (5) is connected to the second electro-optical modulator (EOM) and to control the first driver (5) such that the first driver (5) generates a second control voltage for the second electro-optical modulator (EOM), in a third control step, to control the third and fourth switches (S) such that the second driver (5') is connected to the third electro-optical modulator (EOM) and to control the second driver (5') such that the second driver (5') generates a third control voltage for the third electro-optical modulator (EOM); and in a fourth control step following the third control step, to control the third and fourth switches (S) such that the second driver (5') is connected to the fourth electro-optical modulator (EOM) and to control the second driver (5') such that the second driver (5') generates a fourth control voltage for the fourth electro-optical modulator (EOM), wherein preferably the first and third control steps take place simultaneously and the second and fourth control steps take place simultaneously. [5] Photonic system (1) according to claim 1, characterized by a first group switch (SG1) connected to the first switch (S11) and to the second switch (S1m), wherein the first electro-optical modulator (EOM11) is connectable to the first driver (5) via the first switch (S11) and the first group switch (SG1), wherein the second electro-optical modulator (EOM1m) is connectable to the first driver (5) via the second switch (S1m) and the first group (SG1) switch. [6] Photonic system (1) according to claim 6, characterized by a control unit (4) for controlling the first driver (5) and the first and second switches (S11, S1m) as well as the first group switch (SG1), wherein the control unit (4) is arranged to in a first control step, to control the first and second switches (S11, S1m) and the first group switch (SG1) such that the first driver (5) is connected to the first electro-optical modulator (EOM11) and to control the first driver (5) such that the first driver (5) generates a first control voltage for the first electro-optical modulator (EOM11); and in a second control step following the first control step, to control the first and second switches (S11, S1m) and the first group switch (SG1) in such a way that the first driver (5) is connected to the second electro-optical modulator (EOM1m) and to control the first driver (5) in such a way that the first driver (5) generates a second control voltage for the second electro-optical modulator (EOM1m). [7] Photonic system (1) according to one of claims 5 or 6, characterized by a fifth electro-optical modulator (EOMn1), a fifth switch (Sn1), a sixth electro-optical modulator (EOMnm), a sixth switch (Snm) and a second group switch (SGn) connected to the fifth switch (Sn1) and to the sixth switch (Snm), wherein the fifth electro-optical modulator (EOMn1) is connectable to the first driver (5) via the fifth switch (Sn1) and the second group switch (SGn); and wherein the sixth electro-optical modulator (EOMnm) is connectable to the first driver (5) via the sixth switch (Snm) and the second group switch (SGn). [8] Photonic system (1) according to claim 7, characterized by that the control unit (4) is further configured to control the second group switch (SGn) and is set up to in a third control step, to control the fifth and sixth switches (EOMn1, EOMnm) and the second group switch (SGn) such that the first driver (5) is connected to the fifth electro-optical modulator (EOMn1) and to control the first driver (5) such that the first driver (5) generates a fifth control voltage for the fifth electro-optical modulator (EOMn1); and in a fourth control step following the third control step, to control the fifth and sixth switches (Sn1, Snm) and the second group switch (SGn) in such a way that the first driver (5) is connected to the sixth electro-optical modulator (EOMn1) and to control the first driver (5) in such a way that the first driver (5) generates a sixth control voltage for the sixth electro-optical modulator (EOMnm). [9] Photonic system (1) according to one of the preceding claims, characterized bythat the control unit (4) has a memory (6) for storing control information for the first driver (5) and optionally the second driver (5') and the switches (S1, S11, Sn, S1m) and optionally group switches (SGn). [10] Photonic system (1) according to claim 9, characterized by that the control unit (4) has a processor, wherein the control information in the memory (6) comprises instructions executable by the processor. [11] Photonic system (1) according to one of the preceding claims, characterized by a first supporting capacitance (10), in particular a first capacitor or a dedicated first parasitic capacitance, arranged in parallel with the first electro-optical modulator (EOM, EOM1, EOM11); and a second supporting capacitance (10), in particular a second capacitor or a dedicated second parasitic capacitance, arranged in parallel to the second electro-optical modulator (EOM, EOMn, EOM1m). [12] Photonic system (1) according to claim 9, characterized by that the photonic integrated circuit (PIC) comprises the first and second support capacitance (10). [13] Photonic system (1) according to one of the preceding claims, characterized by that the photonic integrated circuit (PIC) comprises the first and the second switch (S, S1, S11, Sn, S1m). [14] Photonic system according to one of the preceding claims, characterized by that the first switch (S1, S11) and the second switch (Sn, S1m) is a transistor, in particular a field effect transistor, FET. [15] Photonic system (1) according to one of the preceding claims, characterized by that the photonic integrated circuit (PIC) comprises the first driver (5) and optionally the second driver (5'). [16] Photonic system (1) according to one of claims 2 to 15, characterized bythat the first driver (5) and the possibly present second driver (5') are each connected to the control unit (4) via a digital-to-analog converter (7). [17] Method for operating a photonic system (19) with a photonic integrated circuit (PIC) comprising a first and a second electro-optical modulator (EOM, EOM1, EOMn, EOM11, EOM1m), and with a first driver (5) for providing a control voltage for the first and second electro-optical modulator (EOM, EOM1, EOMn, EOM11, EOM1m), wherein the first driver (5) generates a first control voltage in a first control step and this is provided to the first electro-optical modulator (EOM, EOM1, EOM11) via a first switch (S1, S11), and wherein the first driver (5) generates a second control voltage in a second control step following the first control step and this is provided to the second electro-optical modulator (EOM, EOMn, EOM1m) via a second switch (Sn, S1m). [18] Method according to claim 17, characterized by that the first and second control steps are repeated after a predetermined cycle time (T).

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