Patent Publication Number: US-2020278589-A1

Title: Optical architecture with hybrid on-silicon iii-v modulator

Description:
BACKGROUND 
     A silicon photonics-based high-speed modulator may be capable of supporting up to 400 gigabyte per second (Gb/s) based on a phase-amplitude modulation (PAM)-4 modulation scheme with four lanes of up to 100 Gb/s each. In the case of coherent applications, the silicon photonics modulator may be capable of supporting up to 64 gigabaud (GBaud) and 64 quadrature-amplitude modulation (QAM) high-order modulation, therefore supporting up to 600 Gb/s-per-lane with the use of a coherent digital signal processor (DSP). 
     However, a silicon photonics-based modulator may include an intrinsic limitation in areas such as a relatively high half-wave voltage (V pi ). For example, V pi  may be on the order of between 2 volts (V) and 5 V. The silicon photonics modulator may also have a bandwidth on the order of between approximately 20 gigahertz (p) and approximately 40 GHz for both direct PAM-4 and QAM-64 applications. Therefore, it may be difficult to produce low-power and high baud rate devices for operations on the order of terabytes per second (Tb/s). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts an example optical architecture that includes a hybrid modulator, in accordance with various embodiments. 
         FIGS. 2 a  and 2 b    depict an example structure of a photonic transmitter that includes a hybrid modulator, in accordance with various embodiments. 
         FIG. 3  depicts an alternative example optical architecture that includes a hybrid modulator, in accordance with various embodiments. 
         FIG. 4  depicts an alternative example optical architecture that includes a hybrid modulator, in accordance with various embodiments. 
         FIG. 5  depicts an alternative example optical architecture that includes a hybrid modulator, in accordance with various embodiments. 
         FIG. 6  depicts an alternative example optical architecture that includes a hybrid modulator, in accordance with various embodiments. 
         FIG. 7  depicts an alternative example optical architecture that includes a hybrid modulator, in accordance with various embodiments. 
         FIG. 8  is a top view of a wafer and dies that may include a hybrid modulator, in accordance with various embodiments. 
         FIG. 9  is a block diagram of an example electrical device that may include an optical architecture with a hybrid modulator, in accordance with various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, wherein like numerals designate like parts throughout, and in which is shown by way of illustration embodiments in which the subject matter of the present disclosure may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense. 
     For the purposes of the present disclosure, the phrase “A or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C). 
     The description may use perspective-based descriptions such as top/bottom, in/out, over/under, and the like. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of embodiments described herein to any particular orientation. 
     The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments of the present disclosure, are synonymous. 
     The term “coupled with,” along with its derivatives, may be used herein. “Coupled” may mean one or more of the following. “Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements indirectly contact each other, but yet still cooperate or interact with each other, and may mean that one or more other elements are coupled or connected between the elements that are said to be coupled with each other. The term “directly coupled” may mean that two or elements are in direct contact. 
     In various embodiments, the phrase “a first feature [[formed/deposited/disposed/etc.]] on a second feature,” may mean that the first feature is formed/deposited/disposed/etc. over the feature layer, and at least a part of the first feature may be in direct contact (e.g., direct physical or electrical contact) or indirect contact (e.g., having one or more other features between the first feature and the second feature) with at least a part of the second feature. 
     Various operations may be described as multiple discrete operations in turn, in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be construed as to imply that these operations are necessarily order dependent. 
     Embodiments herein may be described with respect to various Figures. Unless explicitly stated, the dimensions of the Figures are intended to be simplified illustrative examples, rather than depictions of relative dimensions. For example, various lengths/widths/heights of elements in the Figures may not be drawn to scale unless indicated otherwise. Additionally, some schematic illustrations of example structures of various devices and assemblies described herein may be shown with precise right angles and straight lines, but it is to be understood that such schematic illustrations may not reflect real-life process limitations which may cause the features to not look so “ideal” when any of the structures described herein are examined, e.g., using scanning electron microscopy (SEM) images or transmission electron microscope (TEM) images. In such images of real structures, possible processing defects could also be visible, e.g., not-perfectly straight edges of materials, tapered vias or other openings, inadvertent rounding of corners or variations in thicknesses of different material layers, occasional screw, edge, or combination dislocations within the crystalline region, and/or occasional dislocation defects of single atoms or clusters of atoms. There may be other defects not listed here but that are common within the field of device fabrication. 
     As noted, a silicon photonics-based modulator may have limitations with respect to areas such as V pi  or bandwidth. One option to address these limitations may be the inclusion of a III-V material-based modulator. One example III-V material may be, for example, indium phosphide (InP). The III-V modulator may have higher modulation bandwidth, for example on the order of 65 GHz or more, and may support greater than 100 GBaud operation with multi Tb/s-per-lane coherent transmission when used in conjunction with a coherent DSP. In addition, the V pi  of the III-V modulator may be made relatively low (e.g., less than 2V. For example, the V pi  of an III-V modulator may be between approximately 1 and approximately 1.5 V), thereby reducing the power consumption of an optical transmission of which the III-V modulator is a part. 
     However, it may be difficult to produce a III-V material-based optical transmitter that is appropriate for coherent applications. For example, it may be difficult to achieve a high-yield/low-loss optical polarization splitter and rotator. Such a splitter or rotator may require many process and regrowth steps to achieve complex functions based on a III-V system. As a result, the yield of such a process may be relatively low and have a relatively high manufacturing cost. It may also be challenging to produce such complex III—V based devices based on available fabrication processes. 
     Embodiments herein relate to resolving the above-described difficulties by incorporating III-V materials such as InP onto a silicon photonics platform, thereby leveraging the strength of both platforms to produce high-speed optical transmitters. Specifically, embodiments herein may relate to a transmitter architecture design that includes a modulator with an increased bandwidth capability. The bandwidth capability may be based on a high-speed III-V epitaxial material that is grown to support a high-speed/low-V pi  III-V material-based modulator. With such a high-speed epitaxial design, several dies that include an epitaxial III-V layer may be placed onto a handling silicon wafer. The handling wafer may be wafer-bonded onto a device silicon wafer. Subsequently, the handling wafer and majority of the III-V epitaxial substrate and layers may be removed, and one or more thin layers of active materials with some number of optical confinement layers may remain. 
     On the silicon device wafer, the optical waveguides may be configured to support a Mach-Zehnder modulator (“MZM”) (e.g., the optical waveguides may diverge to allow for two concurrent optical paths for the optical signal as it traverses the modulator). The epitaxially-grown III-V layer(s) on the device wafer may be designed such that light emitted from a laser (either of the optical transmitter or coupled to the optical transmitter) such that light may be gradually coupled and input to the modulator herein it is modulated by the III-V materials, and the modulated light may then be gradually output and coupled to the output waveguide. 
     Embodiments herein may provide a number of advantages or benefits. For example, embodiments may include benefits from both III-V materials and silicon photonics systems in a single modulator, which may be referred to herein as a “hybrid” modulator. As a result, embodiments may enable ultra high-speed modulation in a silicon photonics platform that is capable of supporting greater than 100 GBaud PAM applications per physical channel and high-capacity coherent QAM applications beyond Tb/s per wavelength. 
     Turning to particular embodiments, configurations of the hybrid modulator may be similar to those of a MZM. Specifically, the hybrid modulator may include two different optical paths through the modulator for a single signal. Based on the interference pattern of the optical paths once they are recombined, data may be encoded into the optical signal to produce a modulated optical signal. In these particular embodiments, the MZM structure may include silicon waveguides on a device wafer, and may further include III-V epitaxial materials which may be a part of the MZM structure. Particularly, the III-V materials may be in alignment with the input and output waveguides of the modulator. In some embodiments, the optical transmitter may include a number of hybrid modulators which may be formed together for coherent applications or non-coherent multiple-channel applications. As used herein, a coherent application may refer to a single-wavelength high-order QAM modulation scheme and a non-coherent application may refer to a multi-channel PAM modulation scheme. 
       FIG. 1  depicts an example optical transmitter architecture that includes a hybrid modulator, in accordance with various embodiments. It will be understood that  FIGS. 1 and 2-7  are intended as highly simplified examples of the architecture of an optical transmitter with respect to how light may propagate through the optical transmitter. The depicted architectures do not depict various active or passive elements such as additional logic, transistors, resistors, capacitors, etc. which may be present in real-world embodiments of the present disclosure. Additionally, although a certain number of structures or elements may be depicted (e.g., a specific number of paths, modulators, splitters, inputs or outputs, monitor photodiodes (MPDs), amplifiers, etc.) other embodiments may have more or fewer than are depicted herein, or elements at different locations in the diagram. As one example, although some embodiments may depict elements such as amplifiers located both prior to, and subsequent to, the modulator, in some embodiments an amplifier may not be present at the input or the output (or both) of the modulator. Additionally, various embodiments are depicted herein for the sake of discussion of various aspects of the present disclosure, but it will be understood that the depictions are intended as non-limiting examples. That is, other embodiments may include combinations of aspects of various of the embodiments. It will also be understood that although signals herein are described as “optical” signals, in some embodiments the signals may be some other type of photonic signal that has, for example, a different frequency or wavelength. 
       FIG. 1  depicts an optical architecture  100 . The optical architecture  100  may have a number n of optical pathways  101   a ,  101   b ,  101   c ,  101   n  (collectively, “optical pathways  101 ”). In some embodiments, n may be between 1 and 32, while in other embodiments n may be higher than 32. The number n of optical pathways  101  may be based on factors such as design characteristics of the optical architecture  100 , the type of device in which the optical architecture  100  (and the corresponding optical transmitter) may be used, etc. Each of the optical pathways  101  may have a bandwidth of at least approximately 200 Gb/s or more. This may be compared to, for example, legacy MZMs which may have a bandwidth on the order of approximately 100 Gb/s. 
     As may be seen, respective ones of the optical pathways  101  may include a signal input  105   a / 105   b / 105   c / 105   n  (collectively, “signal inputs  105 ”). The signal inputs  105  may be inputs wherein an optical signal may be received. In some embodiments, the signal inputs  105  may receive an optical signal from respective lasers (e.g., a different laser for each optical pathway  101 ) while in other embodiments two or more of the signal inputs  105  may receive an optical signal from a single laser after the signal has been split (e.g., by an optical splitter). 
     The optical signal may traverse from a signal input  105  to a splitter such as splitters  110   a / 110   b / 110   c / 110   n  (collectively, “splitters  110 ”). The splitters  110  may split the signal for input to the modulators  115   a / 115   b / 115   c / 115   n  (collectively, “modulators  115 ”). The modulators  115  may be hybrid modulators as described herein. Particularly, the modulators  115  may include an epitaxially-deposited III-V material such as InP on a silicon waveguide substrate as will be described in greater detail with respect to  FIGS. 2 a  and 2 b   . As previously noted, the modulators  115  may be configured to act as a MZM, and so two optical pathways through respective ones of the modulators  115  may be desirable for the operation as previously described. 
     After the optical signal has been modulated by one of modulators  115 , the optical signal may then be recombined by a coupler such as couplers  120   a / 120   b / 120   c / 120   n  (collectively, “couplers  120 ”) which may recombine the signal to form a modulated optical signal. The modulated optical signal may then be output by a signal output such as signal outputs  125   a / 125   b / 125   c / 125   n  (collectively, “signal outputs  125 ”). 
       FIGS. 2 a  and 2 b    depict an example structure of a photonic transmitter that includes a hybrid modulator, in accordance with various embodiments. Specifically,  FIG. 2 a    depicts a cross-sectional view of such a structure, while  FIG. 2 b    depicts an example top-down view of the structure. The modulator  215  may be similar to, for example, one of modulators  115 , and may be coupled with a substrate  203 . 
     The substrate  203  may include a plurality of layers such as the silicon waveguide  213 , a buried oxide layer  218 , and a dielectric material  223 . The substrate  203  may be, for example, considered to be a cored or coreless substrate. The substrate  203  may include one or more layers of the dielectric material  223 . The dielectric material  223  may be organic or inorganic and may be, or include, silicon, a build-up film (ABF) or some other type of dielectric material. The substrate  203  may further include one or more conductive elements such as vias, pads, traces, microstrips, striplines, etc. Various of the conductive elements may be internal to, or on the surface of, the substrate  203 . Generally, the conductive elements may allow for the routing of signals through the substrate  203 , between elements that are coupled to the substrate  203 , etc. In some embodiments the substrate  203  may be, for example, a printed circuit board (PCB), an interposer, a motherboard, or some other type of substrate. 
     As noted, the substrate  203  may include a silicon waveguide  213 . The waveguide  213  may be configured to propagate a signal such as an optical signal  228  through the waveguide  213 . In this embodiment, the silicon waveguide  213  may be or may include silicon, however in other embodiments the waveguide may be or include silicon nitride or some other material. As previously noted, in some embodiments the optical signal  228  may be in a short wavelength spectrum (e.g., having a wavelength between approximately 1200 nanometers (nm) and approximately 1400 nm). In other embodiments, the optical signal  228  may have a different wavelength such as in a longer wavelength spectrum (i.e., between approximately 1500 nm to 1600 nm. The specific wavelength of the optical signal  228  may be based on a factor such as the use case to which the modulator  215  may be put, design considerations, materials used, etc. As may be seen, the waveguide  213  may be positioned in a portion of an optical dielectric material  229  which may be the same type of dielectric material, or a different type of dielectric material, as dielectric material  223 . 
     The substrate  203  may further include the buried oxide layer  218  positioned between the silicon waveguide  213 . The buried oxide layer  218  may be formed of an optical dielectric such as, for example, silicon oxide (SiO 2 ). Specifically, the buried oxide layer  218  may be to prevent leakage of the optical signal  228  from the silicon waveguide  213  into the dielectric material  223 . 
     The modulator  215  may include a III-V material  208 . In some embodiments, the III-V material  208  may be, or include InP. Specifically, the III-V material  208  may be a quantum well (QW) or multiple quantum well (MQW) material such as an indium aluminum gallium arsenide (InAlGaAs) epitaxial layer material on InP. Specifically, the InAlGaAs material may be epitaxially grown on one or more layers of InP. The QW material may, for example, as a way of illustration only, include a range of thirty to thirty-five layers of InAlGaAs wells in layers with an identical thickness of approximately in the range of several nanometers such as from 5 to 7 nm for each QW; and alternate layers of InAlAs barriers with an identical thickness of between approximately from 8 to 10 nm for each of the barriers-. Generally, the number of the barriers may be equals to the number of the QWs plus one additional layer. The wells and barriers may alternate in the QW structure. In other embodiments, a QW material may be, for example, thirty-two layers of InAlGaAs wells and thirty-three layers of InAlAs barriers, wherein the wells and barriers alternate. In other embodiments, the III-V material  208  may be a quantum dot (QD) material or some other type of III-V material. 
     As may be seen, the III-V material  208  of the modulator  215  may be physically or communicatively coupled with the silicon waveguide  213 . As the optical signal  228  propagates through the silicon waveguide  213 , it may transfer into the modulator  215  where it may be modulated to include data that is supplied by a high-speed data source such as a processor, a processor core, a central processing unit (CPU), a high-speed driver that amplifies the incoming data signal to a proper level to drive the modulator, and etc. The now-modulated optical signal  228  may then be output from the modulator  215  back into the silicon waveguide  213  as shown. 
     As shown in  FIG. 2 b   , it will be noted that in some embodiments the modulator  215 , and particularly the III-V material  208 , may be tapered in such a fashion as to facilitate adiabatic transference of the optical signal  228  between the III-V material  208  and the silicon waveguide  213 . In some embodiments, the taper of the III-V material  208  may be in a z-direction (i.e., up and down with respect to the orientation of  FIG. 2 , not shown). In other embodiments, the taper of the III-V material  208  may additionally or alternatively be in a direction perpendicular to the direction of travel of the optical signal and parallel to the silicon waveguide  213 . That is, the III-V material  208  may be tapered as shown in  FIG. 2 b   . In some embodiments, the taper may be such that the III-V material  208  comes to a point as seen in a top-down view of the modulator  215 . Other embodiments may have different types or degrees of tapers. 
     Additionally, as may be noted, in some embodiments the modulator  215  may have a greater width than the width of the silicon waveguide  213 . However, in other embodiments the width of the modulator  215  may be different than as depicted with respect to the width of the silicon waveguide  213 . For example, in some embodiments the modulator  215  may have a same width as, or be narrower than, the silicon waveguide  213 . It will also be noted that the specific degree of taper, the type of taper, or even the existence of the taper may be different in different embodiments. It will also be noted that  FIGS. 2 a  and 2 b    are intended as highly simplified example embodiments, and other embodiments may have additional elements such as additional active, passive, or conductive elements, overmold material, etc. Other variations may be present in other embodiments. 
       FIGS. 3-7  depict alternative example optical architectures that may include a hybrid modulator, in accordance with various embodiments. It will be understood that  FIGS. 3-7  are intended as highly simplified example Figures and may not show each and every element which may be present in such an architecture. Rather, the Figures are intended to show examples of various concepts which may be applied to real-world embodiments. Such real-world embodiments may include additional elements such as active or passive components, conductive elements, etc. Additionally, it will be noted that each and every element of  FIGS. 3-7  may not be enumerated for the sake of lack of redundancy or clutter of the Figures, however (unless expressly noted otherwise), it may be generally assumed that elements that share the same general shape/shading/location as enumerated and discussed elements may have similar features or characteristics 
     Specifically,  FIG. 3  depicts an example optical architecture  300  which may be similar to, and share one or more characteristics with, optical architecture  100 . The optical architecture  300  may include a number of optical paths  301   a ,  301   b ,  301   c , and  301   d  (collectively, “optical paths  301 ”) which may be similar to, and share one or more characteristics with, optical paths  101 . 
     However, as opposed to  FIG. 1  where respective ones of the optical paths  101  may include an individual modulator  115 , the optical architecture  300  may include a single modulator  315  which may span two or more of the optical paths  301  as shown in  FIG. 3 . Such a modulator  315  may be enabled by, for example, include a plurality of waveguides such as waveguide  213  in a single substrate such as substrate  203 . 
       FIG. 4  depicts an example optical architecture  400  which may be similar to, and share one or more characteristics with, optical architectures  100  or  300 . The optical architecture  400  may include a number of optical paths  401   a ,  401   b ,  401   c , and  401   d  (collectively, “optical paths  401 ”) which may be similar to, and share one or more characteristics with, optical paths  101  or  301 . 
     However, in some embodiments the modulator  315  may result in some amount of signal loss of the optical signal as it traverses the modulator. Such a signal loss may be based on, for example, the transition from the silicon waveguide to the modulator (or from the modulator to the silicon waveguide), the act of modulation, or some other factors. Therefore, in some embodiments it may be desirable to amplify the signal either prior to, or subsequent to, the modulator  315 . As shown in  FIG. 4 , the optical architecture may include a plurality of amplifiers  430   a  and  430   b  (collectively, “amplifiers  430 ”). In some embodiments, one or both of the amplifiers  430  may include a material or structure that is similar to that of the modulator  315 . Specifically, in some embodiments one or both of the amplifiers  430  may include a III-V material positioned on a silicon substrate such as substrate  203 . The general shape or configuration of such an amplifier may be similar to that shown with respect to modulator  215 . For example, one or both of the amplifiers  430  may include a tapered portion at one or both ends of the amplifier. In other embodiments, one or both of the amplifiers  430  may be a different type of amplifier. In some embodiments, the III-V material of one or both of the amplifiers  430  may be or include InP as described above in a MQW structure, while in other embodiments one or both of the amplifiers  430  may additionally or alternatively include a QD material and structure or some other types of III-V material. 
     More generally, the amplifiers  430  may include a III-V material  208 . In some embodiments, the III-V material  208  may be, or may include, InP. Specifically, the III-V material  208  may be a QW or MQW material such as an InAlGaAs epitaxial layer material on InP. Specifically, the InAlGaAs material may be epitaxially grown on one or more layers of InP. The QW material may, for example, as a way of illustration only, include three layers of InAlGaAs wells with a thickness of approximately 7 nm for each of the three quantum wells; and alternate layers of InAlAs barriers with a thickness of approximately 10 nm for each of the four barriers. The wells and barriers may alternate in the QW structure. In other embodiments, a QW material may be, for example, five layers of InAlGaAs wells and six layers of InAlAs barriers, wherein the wells and barriers alternate. 
     It will be understood that, as noted above,  FIG. 4  is intended as an example embodiment. In some embodiments, one or both of the amplifiers  430  may be positioned at a different part of the optical architecture  400 . For example, amplifier  430   a  may be positioned between signal input  105   a  and splitter  110   a . Additionally or alternatively, amplifier  430   b  may be positioned between coupler  120   a  and signal output  125   a . In some embodiments, one or both of amplifiers  430  may not be present in the optical architecture  400 . In some embodiments an amplifier  430  may not span each of the optical paths  401 , but rather may be span only a single optical path  401 , or a portion of an optical path  401 . 
       FIG. 5  depicts a more complicated architecture which may be used for an optical architecture  500 . Generally, the optical architecture  500  may be similar to, and share one or more characteristics with, one or more of optical architectures  100 ,  300 , or  400 . For the sake of ease of illustration, elements of optical architecture  100  (or other optical architectures here) such as a splitter  110  or a coupler  120  may not be shown in  FIG. 5  (or other Figures such as  FIGS. 6 and 7 ). However, one of skill in the art will recognize from  FIG. 5  that such elements may still be present, and where those elements may be positioned. 
     The optical architecture  500  may include a signal input  505 , signal output  525 , modulator  515 , and amplifiers  530   a / 530   b  (collectively, “amplifiers  530 ”) which may be respectively similar to, and share one or more characteristics with, signal input  105 , signal output  125 , modulator  115 , and amplifiers  430   a / 430   b.    
     The optical signal may be provided by the signal input, where it may then be split amongst two optical paths  550   a  and  550   b  (collectively “optical paths  550 ”). Respective ones of the optical paths  550  may then be split into different phases. For example, optical paths  555   a  may be in-plane portions of the optical signal, whereas optical paths  555   b  may be quadrature portions of the optical signal. In some embodiments, optical paths  555   b  may include a phase shifter  545  which may shift the optical signal to a quadrature signal. The various signals may then be input to one or more of the amplifiers  530  and modulator  515  where the signal may be modulated or amplified. 
     The modulator  515  may output a plurality of modulated optical signals onto in-phase output paths  560   a  and quadrature output paths  560   b . Similarly to the input side of the optical architecture, there may be an in-phase and a quadrature output paths  560   a / 560   b  for both paths  550  of the optical signal. The modulated optical signals may be combined from the in-phase output path  560   a  and the quadrature output path  560   b  and provided output paths  565   a  and  565   b . The modulated optical signals from output paths  565   a  and  565   b  may be input to a polarization rotator and beam combiner (PRBC)  540  where one of the signals from an output path (e.g., the modulated optical signal from output path  565   a ) may be rotated by 90 degrees such that the two modulated output signals have different polarizations (which may be referred to, for example, as “x-polarization” and “y-polarization”). The polarized and modulated output signals may then be combined to a single modulated optical signal that is provided to signal output  525 . 
     As may be seen in  FIG. 5 , the optical architecture  500  may further include a number of monitor photodiodes (MPDs)  535  at various point along the output side of the optical architecture  500 . The MPDs  535  may be used to monitor the optical power level from either the main output arm or the complimentary arm of each of the interferometers by the use of a coupler-based optical tap from the main output arm or the complimentary arm, and the additional MPD at the tap port. The MPD may be or include a silicon germanium structure or the hybrid III-V die bonded to the silicon wafer at the location of interest. 
     It will be understood that, similarly to other embodiments described herein, the embodiment of  FIG. 5  is intended as an example embodiment, and other embodiments may vary from those depicted. For example, as noted in some embodiments certain of the amplifiers  530  may be missing, or additionally/alternatively in a different location (e.g., at  550   a/b ,  555   a/b ,  560   a/b ,  565   a/b , etc.). In some embodiments, one or more of the modulator  515  or the amplifiers  530  may not span each of the optical paths, but rather there may be a different modulator or amplifier for each of the various input or output paths, phase-related optical paths, or even between different branches of the a MZM. Additionally, on the output side of the optical architecture  500 , the MPDs  535  may be arranged in a different configuration, or there may be a different number of MPDs  535  than are depicted in  FIG. 5 . Other variations may be present in other embodiments. 
       FIG. 6  depicts an alternative example optical architecture  600  which may be generally similar to, and share one or more characteristics with, optical architecture  500  or some other optical architecture herein. Amongst other things,  FIG. 6  may depict an optical architecture  600  with amplifiers  630   a  and  630   b  (collectively referred to as “amplifiers  630 ”) which may be generally similar to, and share one or more characteristics with, amplifiers  430   a  and  430   b  or some other amplifier herein. However, as may be seen by comparing the optical architecture  600  with optical architecture  500 , the amplifiers  630  may be at a different location within the signal path of the optical architecture  600 . Specifically, amplifiers  630   a  may be located in the optical paths  550   a  and  550   b , while amplifier  630   b  may be located at output paths  565   a  and  565   b . As previously noted, it will be realized that this is an example embodiment and other embodiments may vary. For example, the two amplifiers  630   a  may be replaced by a single amplifier that spans both of the optical paths  550   a  and  550   b . Similarly, the single amplifier  630   b  may be replaced by separate amplifiers at respective ones of the output paths  565   a  and  565   b . In some embodiments, the input-side amplifier may be as shown with respect to amplifier  530   a , while the output-side amplifier may be as shown with respect to amplifier  630   b , or vice-versa, or some combination thereof. 
       FIG. 7  depicts an alternative example optical architecture  700  which may be generally similar to, and share one or more characteristics with, optical architecture  500  or some other optical architecture herein. As may be seen, in order to illustrate one example concept related to the present disclosure, optical architecture  700  may not include one or more of the amplifiers such as amplifiers  530   a  or  530   b.    
     As may be seen, the optical architecture  700  may depict variations on modulator configuration which may be present in various embodiments. Specifically, the optical architecture  700  may include a variety of modulators  715   a ,  715   b , and  715   c  (collectively referred to as “modulators  715 ”) which may be similar to, and share one or more characteristics with, modulators  115  or some other modulator herein. As may be seen, a separate III—V based modulator die  715   a  may be present on each of the two optical paths of a MZM. As another example, a single III—V based modulator die  715   b  may span both optical paths of a MZM. As another example, a single III-V based modulator die  715   c  may span a plurality of MZMs, which works in conjunction together with each of the underlining MZM silicon waveguides to form a hybrid MZM in each of the segments. Other embodiments may have other variations. 
     As noted,  FIGS. 1-7  are intended as highly simplified examples, and certain Figures may have certain characteristics that are featured for the sake of discussion herein. However, it will be understood that features of various of the Figures may be combined with features of others of the Figures. 
       FIG. 8  is a top view of a wafer  1500  and dies  1502  that may include one or more hybrid modulators, or may be included in an IC package including one or more hybrid modulators in accordance with various embodiments. The wafer  1500  may be composed of semiconductor material and may include one or more dies  1502  having IC structures formed on a surface of the wafer  1500 . Each of the dies  1502  may be a repeating unit of a semiconductor product that includes a suitable IC. After the fabrication of the semiconductor product is complete, the wafer  1500  may undergo a singulation process in which the dies  1502  are separated from one another to provide discrete “chips” of the semiconductor product. The die  1502  may include one or more hybrid modulators, one or more transistors or supporting circuitry to route electrical signals to the transistors, or some other IC component. In some embodiments, the wafer  1500  or the die  1502  may include a memory device (e.g., a random-access memory (RAM) device, such as a static RAM (SRAM) device, a magnetic RAM (MRAM) device, a resistive RAM (RRAM) device, a conductive-bridging RAM (CBRAM) device, etc.), a logic device (e.g., an AND, OR, NAND, or NOR gate), or any other suitable circuit element. Multiple ones of these devices may be combined on a single die  1502 . For example, a memory array formed by multiple memory devices may be formed on a same die  1502  as a processing device (e.g., the processing device  1802  of  FIG. 9 ) or other logic that is configured to store information in the memory devices or execute instructions stored in the memory array. 
       FIG. 9  is a block diagram of an example electrical device  1800  that may include one or more hybrid modulators, in accordance with any of the embodiments disclosed herein. For example, any suitable ones of the components of the electrical device  1800  may include one or more of the IC device assemblies, IC packages, IC devices, or dies  1502  disclosed herein. A number of components are illustrated in  FIG. 9  as included in the electrical device  1800 , but any one or more of these components may be omitted or duplicated, as suitable for the application. In some embodiments, some or all of the components included in the electrical device  1800  may be attached to one or more motherboards. In some embodiments, some or all of these components are fabricated onto a single system-on-a-chip (SoC) die. 
     Additionally, in various embodiments, the electrical device  1800  may not include one or more of the components illustrated in  FIG. 9 , but the electrical device  1800  may include interface circuitry for coupling to the one or more components. For example, the electrical device  1800  may not include a display device  1806 , but may include display device interface circuitry (e.g., a connector and driver circuitry) to which a display device  1806  may be coupled. In another set of examples, the electrical device  1800  may not include an audio input device  1824  or an audio output device  1808 , but may include audio input or output device interface circuitry (e.g., connectors and supporting circuitry) to which an audio input device  1824  or audio output device  1808  may be coupled. 
     The electrical device  1800  may include a processing device  1802  (e.g., one or more processing devices). As used herein, the term “processing device” or “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory. The processing device  1802  may include one or more DSPs, application-specific integrated circuits (ASICs), CPUs, graphics processing units (GPUs), cryptoprocessors (specialized processors that execute cryptographic algorithms within hardware), server processors, or any other suitable processing devices. The electrical device  1800  may include a memory  1804 , which may itself include one or more memory devices such as volatile memory (e.g., dynamic RAM (DRAM)), nonvolatile memory (e.g., read-only memory (ROM)), flash memory, solid state memory, and/or a hard drive. In some embodiments, the memory  1804  may include memory that shares a die with the processing device  1802 . This memory may be used as cache memory and may include embedded DRAM (eDRAM) or spin transfer torque magnetic RAM (STT-MRAM). 
     In some embodiments, the electrical device  1800  may include a communication chip  1812  (e.g., one or more communication chips). For example, the communication chip  1812  may be configured for managing wireless communications for the transfer of data to and from the electrical device  1800 . The term “wireless” and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a nonsolid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not. 
     The communication chip  1812  may implement any of a number of wireless standards or protocols, including but not limited to Institute for Electrical and Electronic Engineers (IEEE) standards including Wi-Fi (IEEE 802.11 family), IEEE 802.16 standards (e.g., IEEE 802.16-2005 Amendment), Long-Term Evolution (LTE) project along with any amendments, updates, and/or revisions (e.g., advanced LTE project, ultra mobile broadband (UMB) project (also referred to as “3GPP2”), etc.). IEEE 802.16 compatible Broadband Wireless Access (BWA) networks are generally referred to as WiMAX networks, an acronym that stands for Worldwide Interoperability for Microwave Access, which is a certification mark for products that pass conformity and interoperability tests for the IEEE 802.16 standards. The communication chip  1812  may operate in accordance with a Global System for Mobile Communication (GSM), General Packet Radio Service (GPRS), Universal Mobile Telecommunications System (UMTS), High-Speed Packet Access (HSPA), Evolved HSPA (E-HSPA), or LTE network. The communication chip  1812  may operate in accordance with Enhanced Data for GSM Evolution (EDGE), GSM EDGE Radio Access Network (GERAN), Universal Terrestrial Radio Access Network (UTRAN), or Evolved UTRAN (E-UTRAN). The communication chip  1812  may operate in accordance with Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Digital Enhanced Cordless Telecommunications (DECT), Evolution-Data Optimized (EV-DO), and derivatives thereof, as well as any other wireless protocols that are designated as 3G, 4G, 5G, and beyond. The communication chip  1812  may operate in accordance with other wireless protocols in other embodiments. The electrical device  1800  may include an antenna  1822  to facilitate wireless communications and/or to receive other wireless communications (such as AM or FM radio transmissions). 
     In some embodiments, the communication chip  1812  may manage wired communications, such as electrical, optical, or any other suitable communication protocols (e.g., the Ethernet). As noted above, the communication chip  1812  may include multiple communication chips. For instance, a first communication chip  1812  may be dedicated to shorter-range wireless communications such as Wi-Fi or Bluetooth, and a second communication chip  1812  may be dedicated to longer-range wireless communications such as global positioning system (GPS), EDGE, GPRS, CDMA, WiMAX, LTE, EV-DO, or others. In some embodiments, a first communication chip  1812  may be dedicated to wireless communications, and a second communication chip  1812  may be dedicated to wired communications. 
     The electrical device  1800  may include battery/power circuitry  1814 . The battery/power circuitry  1814  may include one or more energy storage devices (e.g., batteries or capacitors) and/or circuitry for coupling components of the electrical device  1800  to an energy source separate from the electrical device  1800  (e.g., AC line power). 
     The electrical device  1800  may include a display device  1806  (or corresponding interface circuitry, as discussed above). The display device  1806  may include any visual indicators, such as a heads-up display, a computer monitor, a projector, a touchscreen display, a liquid crystal display (LCD), a light-emitting diode display, or a flat panel display. 
     The electrical device  1800  may include an audio output device  1808  (or corresponding interface circuitry, as discussed above). The audio output device  1808  may include any device that generates an audible indicator, such as speakers, headsets, or earbuds. 
     The electrical device  1800  may include an audio input device  1824  (or corresponding interface circuitry, as discussed above). The audio input device  1824  may include any device that generates a signal representative of a sound, such as microphones, microphone arrays, or digital instruments (e.g., instruments having a musical instrument digital interface (MIDI) output). 
     The electrical device  1800  may include a GPS device  1818  (or corresponding interface circuitry, as discussed above). The GPS device  1818  may be in communication with a satellite-based system and may receive a location of the electrical device  1800 , as known in the art. 
     The electrical device  1800  may include another output device  1810  (or corresponding interface circuitry, as discussed above). Examples of the other output device  1810  may include an audio codec, a video codec, a printer, a wired or wireless transmitter for providing information to other devices, or an additional storage device. 
     The electrical device  1800  may include another input device  1820  (or corresponding interface circuitry, as discussed above). Examples of the other input device  1820  may include an accelerometer, a gyroscope, a compass, an image capture device, a keyboard, a cursor control device such as a mouse, a stylus, a touchpad, a bar code reader, a Quick Response (QR) code reader, any sensor, or a radio frequency identification (RFID) reader. 
     The electrical device  1800  may have any desired form factor, such as a handheld or mobile electrical device (e.g., a cell phone, a smart phone, a mobile internet device, a music player, a tablet computer, a laptop computer, a netbook computer, an ultrabook computer, a personal digital assistant (PDA), an ultra mobile personal computer, etc.), a desktop electrical device, a server device or other networked computing component, a printer, a scanner, a monitor, a set-top box, an entertainment control unit, a vehicle control unit, a digital camera, a digital video recorder, or a wearable electrical device. In some embodiments, the electrical device  1800  may be any other electronic device that processes data. 
     Examples of Various Embodiments 
     Example 1 includes an electronic device comprising: a signal input to provide an input signal; a splitter to separate the input signal into an in-phase portion of the input signal and a quadrature portion of the input signal; a modulator to modulate the in-phase portion of the input signal and the quadrature portion of the input signal to respectively produce a modulated in-phase portion of the input signal and a modulated quadrature portion of the input signal, wherein the modulator includes a III-V material on a silicon substrate; and a coupler to couple the modulated in-phase portion of the input signal and the modulated quadrature portion of the input signal to form an output signal. 
     Example 2 includes the electronic device of example 1, wherein the III-V material includes InP. 
     Example 3 includes the electronic device of examples 1 or 2, further comprising an amplifier communicatively coupled with the modulator. 
     Example 4 includes the electronic device of example 3, wherein the amplifier is to amplify the input signal, the in-phase portion of the input signal, or the quadrature portion of the input signal. 
     Example 5 includes the electronic device of example 3, wherein the amplifier is to amplify the modulated in-phase portion of the input signal, the modulated quadrature portion of the input signal, or the output signal. 
     Example 6 includes the electronic device of examples 1 or 2, wherein the electronic device further comprises: a second signal input to provide a second input signal; a second splitter to separate the second input signal into an in-phase portion of the second input signal and a quadrature portion of the second input signal; and wherein the modulator is to modulate the in-phase portion of the second input signal and the quadrature portion of the second input signal. 
     Example 7 includes the electronic device of example 6, wherein the first input signal is a first polarization of an optical signal, and the second input signal is a second polarization of the optical signal. 
     Example 8 includes the electronic device of example 7, wherein the electronic device further includes a PRBC communicatively coupled with the coupler. 
     Example 9 includes an electronic device comprising: a splitter to separate an input signal into an in-phase portion and a quadrature portion; a modulator to modulate the in-phase portion of the input signal to produce a modulated in-phase portion, wherein the modulator includes InP on a silicon waveguide; and a coupler to couple the modulated in-phase portion and a modulated quadrature portion of the input signal to produce an output signal. 
     Example 10 includes the electronic device of example 9, wherein the modulator is a MZM. 
     Example 11 includes the electronic device of example 9, further comprising a power source that is to supply a half-wave voltage to the modulator, wherein the half-wave voltage is less than 2 volts. 
     Example 12 includes the electronic device of any of examples 9-11, further comprising a second modulator to modulate the quadrature portion of the input signal to produce a modulated quadrature portion, wherein the second modulator includes InP on a silicon waveguide. 
     Example 13 includes the electronic device of any of examples 9-11, wherein the modulator is further to modulate the quadrature portion of the input signal to produce a modulated quadrature portion. 
     Example 14 includes the electronic device of any of examples 9-11, wherein the modulator is further to modulate the in-phase portion of a second input signal to produce a second modulated in-phase portion. 
     Example 15 includes the electronic device of any of examples 9-11, wherein the electronic device further includes an amplifier communicatively coupled with the modulator. 
     Example 16 includes a MZM comprising: a signal input to receive an unmodulated optical signal; a signal output to output a modulated optical signal that is based on the unmodulated optical signal; a silicon waveguide on a substrate to facilitate transference of the optical signal between the signal input and the signal output; and a III-V material physically coupled with the silicon waveguide. 
     Example 17 includes the MZM of example 16, wherein the modulated optical signal is based on a modulated in-phase component of the unmodulated optical signal or a modulated quadrature component of the unmodulated optical signal. 
     Example 18 includes the MZM of example 16, wherein the modulated optical signal is based on a modulated in-phase component of the unmodulated optical signal and a modulated quadrature component of the unmodulated optical signal. 
     Example 19 includes the MZM of any of examples 16-18, wherein the MZM further comprises: a second signal input to receive a second unmodulated optical signal; and a second signal output to output a second modulated optical signal that is based on the second unmodulated optical signal. 
     Example 20 includes the MZM of any of examples 16-18, wherein the III-V material includes InP. 
     Various embodiments may include any suitable combination of the above-described embodiments including alternative (or) embodiments of embodiments that are described in conjunctive form (and) above (e.g., the “and” may be “and/or”). Furthermore, some embodiments may include one or more articles of manufacture (e.g., non-transitory computer-readable media) having instructions, stored thereon, that when executed result in actions of any of the above-described embodiments. Moreover, some embodiments may include apparatuses or systems having any suitable means for carrying out the various operations of the above-described embodiments. 
     The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or limiting as to the precise forms disclosed. While specific implementations of, and examples for, various embodiments or concepts are described herein for illustrative purposes, various equivalent modifications may be possible, as those skilled in the relevant art will recognize. These modifications may be made in light of the above detailed description, the Abstract, the Figures, or the claims.