Patent Publication Number: US-2023161182-A1

Title: A push-pull device and method for fabricating a push-pull device

Description:
FIELD OF THE INVENTION 
     The present invention relates to a push-pull device and a method for fabricating a push-pull device. In particular, the present invention relates to a push-pull device for differential signals. 
     BACKGROUND ART 
     Push-pull devices, plasmonic devices or plasmonic push-pull devices enable conversion of an electrical signal into an optical signal, or vice versa, respectively modulation of an optical signal in accordance with an electrical signal, or vice versa. Plasmonic devices enable building electro-optic devices having high speed, low optical loss, high modulation depth, compact footprint, and low energy consumption. Plasmonic devices enable high-density integrated circuit solutions. Plasmonic devices may introduce materials with a negative permittivity, e.g. metals, to overcome the diffraction limit, to localize and guide light, and to offer intrinsic high-speed behavior. 
     Baeuerle et al., 120 GBd plasmonic Mach-Zehnder modulator with a novel differential electrode design operated at a peak-to-peak drive voltage of 178 mV, Optics Express, 3 Jun. 2019 and Baeuerle et al., Dual-Drive Plasmonic Transmitter with Co-Designed Driver Electronics operated at 120 GBd On-Off Keying, OFC 2019, Optical Fiber Communication Conference 2019, San Diego, Calif. United States, 3-7 Mar. 2019 disclose a plasmonic dual-drive transmitter. A power multiplexer generates a differential electrical signal which is connected via electrodes with the plasmonic-organic hybrid Mach-Zehnder modulator. Light is coupled via grating couplers to the chip and silicon photonic waveguides direct the light to the plasmonic phase shifters. 
     Wolfgang Heni, Plasmonic-Organic Hybrid Modulators, Diss.-No. ETH 25785, 2019 discloses electric field poling of an organic material of a plasmonic Mach-Zehnder modulator by applying a voltage between the outer electrodes of the modulator. The electric field aligns the molecules of the nonlinear optical material in the direction of the electric field. For device operation, the modulator is contacted by ground-signal-ground microwave probes, wherein the device poling direction and the driving field oppose each other in one slot and point in the same direction in the other slot. 
     DISCLOSURE OF THE INVENTION 
     There may be a need for an improved push-pull device avoiding some drawbacks of the prior art. More particularly, there may be a need for an improved push-pull device with an efficient use of a driving signal. More particularly, there may be a need for an improved push-pull device which is adapted for differential signals. More particularly, there may be a need for an improved push-pull device which is adapted for chip packaging. More particularly, there may be a need for an improved push-pull device which can be fabricated more easily. 
     Such a need may be met with the subject-matter of the independent claims. Advantageous embodiments are defined in the dependent claims. 
     Ideas underlying embodiments of the present invention may be interpreted as being based, inter alia, on the following observations and recognitions. 
     An aspect of the invention relates to a push-pull device, comprising: a first waveguide arranged between a first and a second electrode related to the first waveguide; a second waveguide arranged between a first and a second electrode related to the second waveguide; one or more electrically conductive structures extending away from one or more of the electrodes for electrically connecting at least two of the electrodes, the waveguides and the electrodes originating from a pre-fabrication process, the waveguides being poled by a poling originating from a poling process which includes applying an electrical field between at least two of the electrodes, the electrically conductive structures originating: from the pre-fabrication process, wherein one or more of the electrically conductive structures extend to one or more electrically non-conductive gaps, and wherein the device further comprises one or more electrically conductive elements for electrically connecting two of the electrodes, the electrically conductive elements being related to the electrically non-conductive gaps and originating from a post-fabrication process; and/or from a post-fabrication process. Thus, an arrangement of electrodes and waveguides originates from a pre-fabrication process and enables the poling of the waveguides. An arrangement of electrically conductive structures is arranged for electrically connecting at least two of the electrodes for bringing the push-pull device into operation. After the pre-fabrication process, respective electrodes are electrically disconnected for poling. When the electrically conductive structures originate from the pre-fabrication process, electrically non-conductive gaps provide for disconnection of respective electrodes and electrically conductive elements arranged in a post-fabrication process provide for connecting respective electrodes for putting the push-pull device into operation. The electrically conductive structures may originate from a post-processing process for electrically connecting respective electrodes, wherein there is no need to arrange electrically non-conductive gaps. Putting the push-pull device into operation may include connecting a single ended or a differential signal source. The push-pull device is adapted for chip packaging, because access via bonding wires is enabled. The pre-fabrication process may include a process meeting high quality standards for enabling fabrication of the waveguides, wherein the post-fabrication process may include a fabrication process having lower quality standards. For example, the pre-fabrication process may include a lithographic process meeting high quality standards for enabling fabrication of the waveguides, wherein the post-fabrication process may include a lithographic process not requiring the high quality standards of the pre-fabrication process, or a non-lithographic process, such as a bonding process or a printing process only. In particular, the push-pull device can be fabricated more easily, because after poling the waveguides, the device does not have to undergo any further pre-fabrication process steps. The push-pull device originates from a pre-fabrication process, which is followed by a poling process, which is followed by a post-fabrication process. Because the waveguides are poled, in operation of the device one of the waveguides of the push-pull device relates to the denomination “push” and the other of the waveguides relates to the denomination “pull”. For example, the waveguides relate to two phase modulators, wherein the phase is pushed in one of the waveguides and pulled in the other one. 
     In some embodiments, the push-pull device is a plasmonic dual-drive device. 
     In some embodiments, the push-pull device is a plasmonic push-pull device. 
     In some embodiments, one of the electrically conductive structures extends away from one of the electrodes to a first electrically non-conductive gap, and another one of the electrically conductive structures extends away from another one of the electrodes to the first electrically non-conductive gap. After pre-fabrication, the device is ready for poling. Post-fabrication includes a simple step of arranging an electrically conductive element at the gap, thereby enabling to put the device into operation by connecting a single ended or a differential signal source to the device. 
     In some embodiments, one or more of the electrically conductive structures extends away from one of the electrodes to a first electrically non-conductive gap arranged between the first electrically conductive structure and one of the other electrodes. After pre-fabrication, the device is ready for poling. Post-fabrication includes a simple step of arranging an electrically conductive element at the gap, thereby enabling to put the device into operation by connecting a single ended or a differential signal source to the device 
     An electrically conductive structure extending away from an electrode is electrically connected to this electrode. 
     In some embodiments, one or more of the electrically conductive structures have a lumped design. In particular, the dimensions of the electrically conductive structures are smaller by a factor of more than 10 compared to a radiofrequency wavelength and thereby enable a lumped design having high efficiency. 
     In some embodiments, the second electrode of the first waveguide and the first electrode of the second waveguide are formed from a single electrode. 
     In some embodiments, one or more of the at least one electrically conductive element includes an electrically conductive bonding wire, an electrically conductive printed structure, or an electrical switch. The device is adapted for various configurations. 
     In some embodiments, one or more of the at least one electrically conductive element is arranged at one or more of the at least one electrically non-conductive gap. For example, a bonding wire may be arranged at the electrically non-conductive gap thereby providing a push-pull device originating from a simple fabrication process. 
     In some embodiments, the pre-fabrication process includes a lithographic process falling above a pre-defined quality level and the post-fabrication process includes a lithographic process falling below the pre-defined quality level and/or a non-lithographic process. The pre-defined quality level may relate to a precision, such as defined in nanometers, as regards width and/or length of the waveguides or electrodes, for example. The pre-defined quality level enables fabrication of waveguides which use the plasmonic effect, for example, and requires a highly complex fabrication process, wherein a lithographic process of a lower complexity or no lithographic process is required for arrangement of electrically conductive elements and/or fabrication of the electrically conductive structures. 
     In some embodiments, the waveguides extend essentially along a line or along a ring. A push-pull device is provided which can be designed for various purposes and applications. 
     In some embodiments, the device is configured as one or more of: a plasmonic-organic hybrid device, a plasmonic device, a ferroelectric device, a silicon-organic hybrid electro-optical device, an organic modulator device, a dielectric-organic hybrid device, a transmitter, a phase modulator, a ring modulator, a racetrack modulator, a resonant modulator, a Mach-Zehnder modulator, and an in-phase/quadrature-phase modulator. 
     A method for fabricating a push-pull device comprises: a pre-fabrication process, which includes: arranging a first waveguide between a first and a second electrode related to the first waveguide; arranging a second waveguide between a first and a second electrode related to the second waveguide; optionally arranging one or more electrically conductive structures which extend away from one or more of the electrodes to at least one electrically non-conductive gap. The method further comprises a poling process, which includes applying an electrical field between at least two of the electrodes. The method further comprises a post-fabrication process, which includes in case of optionally arranged conductive structures during the pre-fabrication process, arranging at least one electrically conductive element related to the at least one electrically non-conductive gap for electrically connecting two of the electrodes and/or arranging one or more electrically conductive structures for electrically connecting at least two of the electrodes. 
     In some embodiments, the pre-fabrication process includes arranging one of the electrically conductive structures extending away from one of the electrodes to a first electrically non-conductive gap, and another one of the electrically conductive structures extending away from another one of the electrodes to the first electrically non-conductive gap. 
     In some embodiments, the pre-fabrication process includes arranging one or more of the electrically conductive structures extending away from one of the electrodes to a first electrically non-conductive gap arranged between the first electrically conductive structure and one of the other electrodes. 
     In some embodiments, the pre-fabrication process includes arranging one or more of the electrically conductive structures having a lumped design. 
     In some embodiments, the post-fabrication process includes arranging one or more of the at least one electrically conductive element at one or more of the at least one electrically non-conductive gap. 
     In some embodiments, the pre-fabrication process includes a lithographic process falling above a pre-defined quality level and the post-fabrication process includes a lithographic process falling below the pre-defined quality level and/or a non-lithographic process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following, advantageous embodiments of the invention will be described with reference to the enclosed drawings. However, neither the drawings nor the description shall be interpreted as limiting the invention. 
         FIG.  1    schematically illustrates elements of an embodiment of a push-pull device originating from a pre-fabrication process. 
         FIG.  2    schematically illustrates the push-pull device of  FIG.  1    having poled waveguides originating from a poling process. 
         FIG.  3    schematically illustrates the push-pull device of  FIG.  3    having elements originating from a post-fabrication process. 
         FIG.  2   ′ schematically illustrates a push-pull device having poled waveguides originating from a poling process. 
         FIG.  3   ′ schematically illustrates the push-pull device of  FIG.  2   ′ having electrically conductive structure originating from a post-fabrication process. 
         FIGS.  4 - 7    schematically illustrate embodiments of push-pull devices originating from a pre-fabrication process, a poling process and a post-fabrication process. 
         FIG.  8    schematically illustrates elements of an embodiment of a push-pull device originating from a pre-fabrication process and having poled waveguides origination from a poling process. 
         FIG.  9    schematically illustrates the push-pull device of  FIG.  8    having elements originating from a post-fabrication process. 
         FIG.  10    schematically illustrates elements of an embodiment of a push-pull device having a ring design originating from a pre-fabrication process and having poled waveguides origination from a poling process. 
         FIG.  11    schematically illustrates the push-pull device of  FIG.  10    having elements originating from a post-fabrication process. 
         FIG.  12    schematically illustrates elements of an embodiment of a push-pull device having a ring design originating from a pre-fabrication process and having poled waveguides origination from a poling process. 
         FIG.  13    schematically illustrates the push-pull device of  FIG.  12    having elements originating from a post-fabrication process. 
         FIG.  14    schematically illustrates elements of an embodiment of a push-pull device having a waveguides extending along a line and having multiple photonic waveguides originating from a pre-fabrication process and having poled waveguides origination from a poling process. 
         FIG.  15    schematically illustrates the push-pull device of  FIG.  14    having elements originating from a post-fabrication process. 
         FIGS.  16 A,  16 B,  16 C  schematically illustrate a cross-section view of possible configurations of a push-pull device  10  connected with a chip device  20 . 
     
    
    
     The figures are only schematic and not to scale. Same reference signs refer to same or similar features. Same schematic elements refer to same or similar features. 
     MODE(S) FOR CARRYING OUT THE INVENTION 
       FIG.  1    schematically illustrates waveguides W 1 , W 2 , electrodes S 11 , S 12 , S 21 , S 22  and electrically conductive structures T 11 , T 22  of a push-pull device  10 . The waveguides W 1 , W 2 , the electrodes S 11 , S 12 , S 21 , S 22  and the electrically conductive structures T 11 , T 22  originate from a pre-fabrication process. In other embodiments not illustrated in  FIG.  1   , the waveguides W 1 , W 2  and the electrodes S 11 , S 12 , S 21 , S 22  originate from a pre-fabrication process, whereas the electrically conductive structures T 11 , T 22  originate from a post-fabrication process. 
     A first waveguide W 1  is arranged between a first and a second electrode S 11 , S 22  related to the first waveguide W 1 . A second waveguide W 2  is arranged between a first and a second electrode S 21 , S 22  related to the second waveguide W 2 . The waveguides W 1 , W 2  essentially extend along respective lines arranged essentially parallel to each other. Accordingly, the waveguides W 1 , W 2  and electrodes S 11 , S 12 , S 21 , S 22  are arranged in a direction perpendicular to these lines. As illustrated in  FIG.  1   , the second electrode S 12  of the first waveguide W 1  and the first electrode S 21  of the second waveguide W 2  may be formed from a single electrode. A first electrically conductive structure T 11  extends away from the first electrode S 11  of the first waveguide W 1  to an electrically non-conductive gap G 1 . A second electrically conductive structure T 22  extends away from the second electrode S 22  of the second waveguide W 2  to the electrically non-conductive gap G 1 . The electrically conductive structures T 11 , T 22  abut the respective electrodes S 11 , S 22  and are electrically connected to the respective electrodes S 11 , S 22 . 
       FIG.  2    schematically illustrates the first waveguide W 1  and the second waveguide W 2  of the push-pull device  10  being poled by a poling P originating from a poling process which includes applying an electrical field between at least two of the electrodes S 11 , S 12 , S 21 , S 22 . As illustrated in  FIG.  2   , applying an electrical field between at least two of the electrodes S 11 , S 12 , S 21 , S 22  includes connecting a positive voltage V+ to the first electrode S 11  of the first waveguide W 1  and a negative voltage V− to the second electrode S 22  of the second waveguide W 2 . As illustrated in  FIG.  2   , the direction of the poling P is in the same direction in the first waveguide W 1  and in the second waveguide W 2 . 
       FIG.  3    illustrates schematically an electrically conductive element C 1  being arranged at the electrically non-conductive gap G 1  for electrically connecting the first electrode S 11  of the first waveguide W 1  and the second electrode S 22  of the second waveguide W 2 , in particular via the first electrically conductive structure T 11  of the first waveguide W 1  and the second electrically conductive structure T 22  of the second waveguide W 2 . As illustrated in  FIG.  3   , a driving voltage U+, U− may be connected to the electrically conductive element C 1  and the electrodes S 12 , S 21  for generating a driving field D in the waveguides W 1 , W 2 . The electrically conductive element C 1  originates from a post-processing process. In other embodiments not illustrated in  FIG.  3   , the driving voltage U+, U− may be connected to the electrodes S 11 , S 22  or the electrically conductive structures T 11 , T 22  and the electrodes S 12 , S 21  for generating a driving filed D in the waveguides W 1 , W 2 . 
     The electrically non-conductive gap G 1  enables the poling P of the first waveguide W 1  and of the second waveguide W 2 , and the electrically conductive element C 1  arranged at the electrically non-conductive gap G 1  enables applying a driving field D to the first waveguide W 1  and to the second waveguide W 2  by connecting a driving voltage U+, U−, such as a single-ended signal or differential signal, to the electrodes S 12 , S 21  and the electrically conductive element C 1 , for example. The direction of the poling P is the same in both waveguides W 1 , W 2 , wherein the direction of the driving field D in the first waveguide W 1  is opposite to the driving field D in the second waveguide W 2 . Optical signals L 1 , L 2  may be coupled into the waveguides W 1 , W 2  at one end, and modified optical signals L 1 ′, L 2 ′ may be received from the waveguides W 1 , W 2  at the other end, wherein the modified optical signals L 1 ′, L 2 ′ are modified in accordance to the driving field D generated by the driving voltage U+, U− in the respective waveguides W 1 , W 2 . The plasmonic  10  device is adapted for chip packaging. The push-pull device  10  can be fabricated more easily. 
     In accordance to the invention, the waveguides W 1 , W 2 , the electrodes S 11 , S 12 , S 21 , S 22 , and the electrically conductive structures T 11 , T 22  originate from a pre-fabrication process, and the electrically conductive element C 1  originates from a post-fabrication process. In particular, the pre-fabrication process requires high precision, wherein the precision requirements of the poling process and the post-fabrication process is less demanding. The push-pull device  10  can be fabricated in a sequence of three fabrication processes. After the poling process there is no need to bring back the push-pull device  10  to a fabrication process which requires high precision for enabling connection of a driving voltage U+, U− to the push-pull device  10 . Merely by arranging the electrically conductive element C 1  in a post-fabrication process, it is enabled that the push-pull device  10  can be put into operation by connecting a driving voltage U+, U−. 
       FIG.  4    illustrates schematically an embodiment of a push-pull device  10 . The first electrically conductive structure T 11  of the first waveguide W 1  extends away from the first electrode S 11  of the first waveguide W 1  to an electrically non-conductive gap G 1  arranged between the first electrically conductive structure T 11  and the second electrode S 22  of the second waveguide W 2 . After poling P of the waveguides W 1 , W 2 , the electrically conductive element C 1  is arranged at the electrically non-conductive gap G 1  for electrically connecting the first electrode S 11  of the first waveguide W 1  and the second electrode S 22  of the second waveguide W 2 , in particular via the first electrically conductive structure T 11 . The push-pull device  10  can be put into operation by connecting a driving voltage U+, U− to the electrodes S 12 , S 21  and the first electrically conductive structure T 11 , for example. 
       FIG.  2   ′ illustrates schematically an embodiment of a push-pull device  10 . A first waveguide W 1  is arranged between a first and second electrode S 11 , S 12  related to the first waveguide W 1 . A second waveguide W 2  is arranged between a first and a second electrode S 21 , S 22  related to the second waveguide W 2 . The waveguides W 1 , W 2  and the electrodes S 11 , S 12 , S 21 , S 22  originate from a pre-fabrication process. The waveguides W 1 , W 2  are poled by a poling P originating from a poling process which includes applying an electrical field between at least two of the electrodes S 11 , S 12 , S 21 , S 22 . As illustrated in  FIG.  2   ′, applying an electrical field between at least two of the electrodes S 11 , S 12 , S 21 , S 22  includes connecting a positive voltage V+ to the first electrode S 11  of the first waveguide W 1  and a negative voltage V− to the second electrode S 22  of the second waveguide W 2 . As illustrated in  FIG.  2   , the direction of the poling P is in the same direction in the first waveguide W 1  and in the second waveguide W 2 . 
       FIG.  3   ′ illustrates schematically an electrically conductive structure T 11  being arranged for electrically connecting the first electrode S 11  of the first waveguide W 1  and the second electrode S 22  of the second waveguide W 2 . The electrically conductive structure T 11  originates from a post-fabrication process. As illustrated in  FIG.  3   ′, a driving voltage U+, U− may be connected to the electrically conductive structure T 11  and the electrodes S 12 , S 21  for generating a driving field D in the waveguides W 1 , W 2 . 
       FIG.  5    illustrates schematically an embodiment of a push-pull device  10 . The second electrode S 12  of the first waveguide W 1  is arranged separated from the first electrode S 21  of the second waveguide W 2 . A first electrically conductive structure T 11  of the first waveguide W 1  extends away from the first electrode S 11  of the first waveguide W 1  to a first electrically non-conductive gap G 1 . A second electrically conductive structure T 22  of the second waveguide W 2  extends away from the second electrode S 22  of the second waveguide W 2  to the first electrically non-conductive gap G 1 . Analogously, a second electrically conductive structure T 12  of the first waveguide W 1 , a first electrically conductive structure T 21  of the second waveguide W 2 , and a second electrically non-conductive gap G 2  are arranged. Poling P may originate, for example, from applying an electrical field between the first and the second electrode S 11 , S 12  of the first waveguide W 1 , and by applying an electrical field between the first and second electrode S 21 , S 22 , of the second waveguide W 2 . A first electrically conductive element C 1  is arranged at the electrically non-conductive gap G 1  for electrically connecting the first electrode S 11  of the first waveguide W 1  and the second electrode S 22  of the second waveguide W 2 , in particular via the first electrically conductive structure T 11  of the first waveguide W 1  and the second electrically conductive structure T 22  of the second waveguide W 2 . A second electrically conductive element C 2  is arranged at the second electrically non-conductive gap G 2  for electrically connecting the second electrode S 12  of the first waveguide W 1  and the first electrode S 21  of the second waveguide W 2 , in particular via the second electrically conductive structure T 12  of the first waveguide W 1  and the first electrically conductive structure T 21  of the second waveguide W 2 . The push-pull device  10  can be put into operation by connecting a driving voltage U+, U− to the first and the second electrically conductive element C 1 , C 2 , for example. 
       FIG.  6    illustrates schematically an embodiment of a push-pull device  10 . The second electrode S 12  of the first waveguide W 1  is arranged separated from the first electrode S 21  of the second waveguide W 2 . A first electrically conductive structure T 11  of the first waveguide W 1  extends away from the first electrode S 11  of the first waveguide W 1  to a first electrically non-conductive gap G 1 . A first electrically conductive structure T 22  of the second waveguide W 2  extends away from the first electrode S 21  of the second waveguide W 2  to the first electrically non-conductive gap G 2 . Analogously, a second electrically conductive structure T 12  of the first waveguide W 1 , a second electrically conductive structure T 22  of the second waveguide W 2 , and a second electrically non-conductive gap G 2  are arranged. As illustrated in  FIG.  6   , poling P originates from applying an electrical field between the first electrodes S 11 , S 21  of the first and second waveguides W 1 , W 2 , and by applying an electrical field between the second electrodes S 12 , S 22 , of the first and second waveguides W 1 , W 2 . As illustrated in  FIG.  6   , a positive voltage V+ is connected to the first electrically conductive structure T 11  of the first waveguide W 1  and a negative voltage V− is connected to the first electrically conductive structure T 21  of the second waveguide W 2 . As illustrated in  FIG.  6   , the positive voltage V+ is connected to the second electrically conductive structure T 22  of the second waveguide W 2  and the negative voltage V− is connected to the second electrically conductive structure T 12  of the first waveguide W 1 . Accordingly, the direction of the poling P is in one direction in the first waveguide W 1  and in the opposite direction in the second waveguide W 2 . 
       FIG.  7    illustrates the embodiment of a push-pull device  10  in accordance with  FIG.  6   , wherein a first electrically conductive element C 1  is arranged at the electrically non-conductive gap G 1  for electrically connecting the first electrode S 11  of the first waveguide W 1  and the first electrode S 21  of the second waveguide W 2 , in particular via the first electrically conductive structure T 11  of the first waveguide W 1  and the first electrically conductive structure T 21  of the second waveguide W 2 . A second electrically conductive element C 2  is arranged at the second electrically non-conductive gap G 2  for electrically connecting the second electrode S 12  of the first waveguide W 1  and the second electrode S 22  of the second waveguide W 2 , in particular via the second electrically conductive structure T 12  of the first waveguide W 1  and the second electrically conductive structure T 22  of the second waveguide W 2 . The push-pull device  10  can be put into operation by connecting a driving voltage U+, U− to the first and the second electrically conductive element C 1 , C 2 , for example. 
       FIG.  8    illustrates schematically an embodiment of a push-pull device  10 . Illustrated are elements of the push-pull device  10  as arranged on an integrated chip. The push-pull device  10  includes waveguides W 1 , W 2 , electrodes S 11 , S 12 , S 21 , S 22  electrically conductive structures T 11 , T 22 , and an electrically non-conductive gap G 1  originating from a pre-fabrication process. The push-pull device  10  illustrated in  FIG.  8    corresponds to the push-pull device  10  illustrated in  FIG.  2   . As illustrated in  FIG.  8   , at the location of the electrically non-conductive gap G 1 , the electrically conductive structures T 11 , T 22  extend into a form of a bonding pad, in particular a negative signal bonding pad O−. Furthermore, other bonding pads are arranged, in particular ground pad Gnd and a positive signal bonding pad 0+, which is connected via an electrically conductive structure to the electrodes S 12 , S 21 . As illustrated in  FIG.  8   , poling of the waveguides W 1 , W 2  is provided by connecting voltages V+, V− to the electrically conductive structures T 11 , T 22  at the location of the negative signal bonding pads O−. 
       FIG.  9    illustrates the embodiment of a push-pull device  10  in accordance with  FIG.  8   , wherein a first electrically conductive element C 1  is arranged at the electrically non-conductive gap G 1  for electrically connecting the first electrode S 11  of the first waveguide W 1  and the second electrode S 22  of the second waveguide W 2 , in particular via the first electrically conductive structure T 11  of the first waveguide W 1  and the second electrically conductive structure T 22  of the second waveguide W 2 . The push-pull device  10  can be put into operation by connecting a driving voltage U+, U− to the positive bonding pad O+ and to the electrically conductive element C 1 , for example. 
       FIG.  10    illustrates schematically an embodiment of a push-pull device  10 , which includes a first waveguide W 1  arranged between a first and a second electrode S 11 , S 12  related to the first waveguide W 1  and a second waveguide W 2  arranged between a first and a second electrode S 21 , S 22  related to the second waveguide W 2 . The waveguides W 1 , W 2  have a ring/racetrack design. Accordingly, each of the waveguides W 1 , W 2  and the respective electrodes S 11 , S 12 , S 21 , S 22  are arranged concentrically. The second electrode S 12  of the first waveguide W 1  and the first electrode S 21  of the second waveguide W 2  are connected to each other by respectively arranged electrode parts, for example a rectangular electrode part as illustrated in  FIG.  10   . A first electrically conductive structure T 11  extends away from the first electrode S 11  of the first waveguide W 1  to an electrically non-conductive gap G 1 . A second electrically conductive structure T 22  extends away from the second electrode S 22  of the second waveguide W 2  to the electrically non-conductive gap G 1 . The conductive structures T 11 , T 22  are arranged at a distance from the respective electrodes S 11 , S 22 , in particular because the respective electrodes S 11 , S 22  are arranged inside the waveguides W 1 , W 2  and the respective other electrodes S 12 , S 21 . The waveguides W 1 , W 2 , the electrodes S 11 , S 12 , S 21 , S 22  and the electrically conductive structures T 11 , T 22  originate from a pre-fabrication process. 
     The push-pull device  10  illustrated in  FIG.  10    includes two resonant plasmonic waveguides W 1 , W 2  which are connected by a feeding photonic waveguide G which also acts as in- and output to the push-pull device  10 . The resonant plasmonic waveguides W 1 , W 2  have a ring/racetrack design. The photonic waveguide G interfaces the waveguides W 1 , W 2  and may be arranged below or above the waveguides W 1 , W 2  for coupling an optical signal to/from the resonant structure. 
     As illustrated in  FIG.  10   , a photonic waveguide G is arranged, which extends in a diagonal direction between the first waveguide W 1  and the second waveguide W 2 . The photonic waveguide G enables receiving an optical signal L at one end and transmitting a modulated optical signal L′ at the other end. 
     As illustrated in  FIG.  10   , the electrically conductive structures T 11 , T 22  are connected with the respective electrodes S 11 , S 22 . This connection may be arranged above or below the layer with the waveguides W 1 , W 2  and/or the electrodes S 11 , S 12 , S 21 , S 21 . 
     As illustrated in  FIG.  10   , the waveguides W 1 , W 2  are poled by a poling P originating from a poling process which includes applying an electrical field between at least two of the electrodes S 11 , S 12 , S 21 , S 22 . As illustrated in  FIG.  10   , applying an electrical field between at least two of the electrodes S 11 , S 12 , S 21 , S 22  includes connecting voltages V+, V− to the electrically conductive structures T 11 , T 22 . 
       FIG.  11    illustrates schematically an electrically conductive element C 1  being arranged at the electrically non-conductive gap G 1  for electrically connecting the first electrode S 11  of the first waveguide W 1  and the second electrode S 22  of the second waveguide W 2 , in particular via the first electrically conductive structure T 11  of the first waveguide W 1  and the second electrically conductive structure T 22  of the second waveguide W 2 . As illustrated in  FIG.  11   , a driving voltage U+, U− may be connected to the electrically conductive element C 1  and the electrodes S 12 , S 21  for generating a driving field D in the waveguides W 1 , W 2 . The electrically conductive element C 1  originates from a post-processing process. 
       FIGS.  12 ,  13    illustrate schematically an embodiment of a push-pull device  10  having similar features as the push-pull device  10  illustrated in  FIGS.  10 ,  11   . The second electrode S 12  of the first waveguide W 1  and the first electrode S 21  of the second waveguide W 2  are arranged separated by a distance from each other. Thus, the electrodes S 12 , S 22  are electrically disconnected. The electrically conductive structures T 11 , T 22  extend from the electrodes S 12 , S 22  and are arranged without a gap, for example in the form of a single electrically conductive structure. The waveguides W 1 , W 2  and the electrodes S 11 , S 12 , S 21 , S 22  originate from a pre-fabrication process, as well as, for example, the electrically conductive structures T 11 , T 22 . The waveguides W 1 , W 2  are poled by a poling P originating from a poling process which includes applying an electrical field between at least two of the electrodes S 11 , S 12 , S 21 , S 22 . As illustrated in  FIG.  12   , applying an electrical field between at least two of the electrodes S 11 , S 12 , S 21 , S 22  includes connecting voltages V+, V− to the electrodes S 11 , S 22 . As illustrated in  FIG.  13   , electrically conductive structures T 21 , T 22  are arranged for connecting the electrodes S 12 , S 21 . The electrically conductive structures T 21 , T 22  originate, for example, from a post-fabrication process. The push-pull device  10  can be put into operation by connecting a driving voltage U+, U− to the electrically conductive structures T 11 , T 22  and the electrically conductive structures T 21 , T 22 , for example. 
       FIGS.  14 ,  15    illustrate schematically an embodiment of a push-pull device  10  having similar features as the push-pull device  10  illustrated in  FIGS.  1 - 3   . The push-pull device  10  illustrated in  FIGS.  14 ,  15    is a resonant device. Arranged are photonic waveguides G, wherein a linear photonic waveguide G is arranged, in the illustrated embodiment, essentially on the symmetry axis of the push-pull device  10 , and on each side of the symmetry axis a photonic waveguide having a ring/racetrack design is arranged, which have sections which coincide with the waveguides W 1 , W 2 . Other embodiments of the push-pull device  10  may have arranged waveguides G in different configurations. 
       FIGS.  16 A,  16 B,  16 C  illustrate schematically a cross-section view of possible configurations of a push-pull device  10  connected with a chip device  20 . The chip device  20  may relate to an electronic chip, an interposer, or a signal source, for example. Exemplary electrical connections between the push-pull device  10  and the chip device  20  are illustrated with lines or curves having bullets at their ends, which are not limiting the number of connections, physical features of the connections, etc. 
       FIG.  16 A  illustrates contacting, in a post-fabrication process, the chip device  20  with electrodes S . . . , electrically conductive structures T . . . and/or contact elements C . . . arranged on the push-pull device  10  having waveguides W 1 , W 2  and originating from a pre-fabrication process, a poling process and a post-fabrication process. 
       FIG.  16 B  illustrates contacting, in a post-fabrication process, for example a wafer-bonding process, a ball bonding process, etc., electrically conductive structures T . . . arranged on the chip device  20  with electrodes S . . . arranged on the push-pull device  10  having waveguides W 1 , W 2  and originating from a pre-fabrication process and a poling process. 
       FIG.  16 C  illustrates arranging, in a post-fabrication process, for example including bonds, printed structures, etc., electrically conductive structures T . . . for contacting the chip device  20  with electrodes S . . . arranged on the push-pull device  10  having waveguides W 1 , W 2  and originating from a pre-fabrication process and a poling process. 
       FIGS.  1 - 9    illustrate embodiments of push-pull devices having a linear design, wherein the waveguides W 1 , W 2  essentially extend along a line. 
       FIGS.  10 - 13    illustrate embodiments of push-pull devices having a ring/racetrack design, wherein the waveguides W 1 , W 2  essentially extend along a ring, further including a photonic waveguide G having a linear design. Other embodiments of the push-pull device may have a photonic waveguide G of a different design, for example including curvatures, etc. 
       FIGS.  14 - 15    illustrate embodiments of push-pull devices having waveguides W 1 , W 2  which essentially extend along a line, further including photonic waveguides essentially extending along a line and along rings/racetracks. 
       FIGS.  2   ′,  3 ′ illustrates an embodiment of a push-pull device analogous to the push-pull device illustrated in  FIGS.  2 ,  3   , wherein the electrically conductive structure T 11  originates from a post-fabrication process. Analogously, the push-pull devices illustrated in  FIGS.  1 - 15    may include electrically conductive structures T 11 , T 12 , T 21 , T 22  originating from a post-fabrication process. 
     The push-pull device  10  according to the present disclosure may include electrodes S 11 , S 12 , S 21 , S 22  with one or more metal layers comprising or consisting of Gold (Au), Silver (Ag), Copper (Cu), Aluminium (Al), or Titanium (Ti), Chromium (Cr), or an alloy thereof. In some embodiments, a high permittivity material, such as BaTiO3, may be arranged, for example between the waveguides W 1 , W 2  and the electrodes S 11 , S 12 , S 21 , S 22 , for providing a capacitive coupling. 
     The push-pull device  10  according to the present disclosure may include waveguides W 1 , W 2  with a dielectric layer, a semiconductor, an insulating material, etc. In some embodiments, the waveguides W 1 , W 2  make use of the plasmonic effect. In some embodiments, the waveguides W 1 , W 2  are silicon-organic hybrid waveguides. In some embodiments, the waveguides W 1 , W 2  are all-organic waveguides. In some embodiments, the waveguides W 1 , W 2  are silicon-nitride organic waveguides. The dielectric layer may be formed by a semiconducting or insulating material, such as Silicon, Silicon Nitride, Silicon Oxide, Aluminum Oxide, Titanium Oxide, Hafnium Oxide, Titanium Nitride, Germanium, Indium Gallium Arsenide, or a material containing nanoparticles, organic materials, ferroelectric materials, materials featuring a second-order non-linearity, or liquid crystals. 
     The push-pull device  10  according to the present disclosure may include electrically conductive structures T 11 , T 12 , T 21 , T 22  formed from a conductive material, such as one or more metal layers comprising or consisting of Gold (Au), Silver (Ag), Copper (Cu), Aluminium (Al), or Titanium (Ti), Chromium (Cr), Tantalum (Ta), Tungsten (W), Palladium (Pd), Platinum (Pt), or an alloy thereof, or other conductive materials such as semiconducting materials. 
     Applying an electrical field to the electrodes S 11 , S 12 , S 21 , S 22  for establishing poling P of the waveguides W 1 , W 2  of the push-pull device  10  according to the present disclosure may include connecting voltages V+, V− to electrodes S 11 , S 12 , S 21 , S 22 . Furthermore and/or alternatively, the voltages V+, V− may be connected to electrically conductive structures T 11 , T 12 , T 21 , T 22 . Furthermore, first voltages V+, V− may be connected to first electrodes S 11 , S 12 , S 21 , S 22 /electrically conductive structures T 11 , T 12 , T 21 , T 22 , and second voltages V+, V− may be connected to second pair electrodes S 11 , S 12 , S 21 , S 22 /electrically conductive structures T 11 , T 12 , T 21 , T 22 . Furthermore, one or more of the electrodes S 11 , S 12 , S 21 , S 22 /electrically conductive structures T 11 , T 12 , T 21 , T 22  may be connected to ground. 
     The push-pull device  10  according to the present disclosure may include electrically conductive elements C 1 , C 2  which include bonding wires, electrically conductive printed structures, conductive thin-films, or an electrical switch. 
     The push-pull device  10  according to the present disclosure may include electrically conductive structures T 11 , T 12 , T 21 , T 22  which have dimensions that are smaller by a factor of more than 10 compared to a radiofrequency wavelength and therefore having a lumped design. 
     The push-pull device  10  according to the present disclosure may include waveguides W 1 , W 2  and electrodes S 11 , S 21 , S 21 , S 22  which originate from a pre-fabrication process which includes a lithographic process. 
     The push-pull device  10  according to the present disclosure may include electrically conductive structures T 11 , T 12 , T 21 , T 22  which originate from a pre-fabrication process which includes a lithographic process or from a post-fabrication process which includes a lithographic or a non-lithographic process. 
     The push-pull device  10  according to the present disclosure may include electrically conductive elements C 1 , C 2  which originate from a post-fabrication process which includes a lithographic or a non-lithographic process. 
     In some embodiments, the waveguides W 1 , W 2  and the electrodes S 11 , S 12 , S 21 , S 22  originate from a pre-fabrication process which may include electron beam lithography and a liftoff process applied to e-beam evaporated gold, and/or a negative tone electron-beam resist may be used. 
     Finally, it should be noted that the term “comprising” does not exclude other elements or steps and the “a” or “an” does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.