Patent Publication Number: US-11394094-B2

Title: Waveguide connector having a curved array of waveguides configured to connect a package to excitation elements

Description:
CROSS-REFERENCE TO THE RELATED APPLICATIONS 
     This patent application is a U.S. National Phase Application under 35 U.S.C. § 371 of International Application No. PCT/US2016/054900, filed on Sep. 30, 2016, the entire contents of which is hereby incorporated by reference herein. 
     TECHNICAL FIELD 
     The present disclosure relates to systems and methods for coupling waveguides to package substrates. 
     BACKGROUND 
     As more devices become interconnected and users consume more data, the demand placed on servers accessed by users has grown commensurately and shows no signs of letting up in the near future. Among others, these demands include increased data transfer rates, switching architectures that require longer interconnects, and extreme cost and power efficient solutions. 
     There are many interconnects within server and high performance computing (HPC) architectures today. These interconnects include within blade interconnects, within rack interconnects, and rack-to-rack interconnects or rack-to-switch interconnects. In today&#39;s architectures, short interconnects (for example, within rack interconnects and some rack-to-rack interconnects) are achieved with electrical cables—such as Ethernet cables, co-axial cables, or twin-axial cables, depending on the required data rate. For longer distances, optical solutions are employed due to the very long reach and high bandwidth enabled by fiber optic solutions. However, as new architectures emerge, such as 100 Gigabit Ethernet, traditional electrical connections are becoming increasingly expensive and highly power consuming to support the required data rates and transmission range. For example, to extend the reach of a cable or the given bandwidth on a cable, higher quality cables may need to be used or advanced equalization, modulation, and/or data correction techniques employed which add power and latency to the system. For some distances and data rates required in proposed architectures, there is no viable electrical solution today. Optical transmission over fiber is capable of supporting the required data rates and distances, but at a severe power and cost penalty, especially for short to medium distances, such as a few meters. 
     Waveguides have not been used in modern server and HPC architectures in part because the compact nature of these architectures require some degree of flexibility in the chosen interconnect methods. With modern assembly and implementation methods, when waveguides are bent, some cross-sectional deformation is common. As waveguides largely rely on a consistent cross-section for signal integrity, even slight deformation often results in levels of signal degradation that are unacceptable for most server and HPC applications. Also, as signal frequencies increase, waveguides&#39; dimensions decrease. As dimensions decrease, alignment tolerances become stricter. Thus, using current systems and methods, optical waveguides are difficult to reliably and appropriately connect to their source at the scales these applications demand. Further, as data rates increase, signal degradation tolerances tend to decrease, so today&#39;s electrical waveguides and their assembly methods are trending to become even less feasible for these applications in the future. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features and advantages of various embodiments of the claimed subject matter will become apparent as the following Detailed Description proceeds, and upon reference to the Drawings, wherein like numerals designate like parts throughout the specification description, and in which: 
         FIG. 1A  illustrates a view of an example waveguide connector in accordance with at least one embodiment described herein; 
         FIG. 1B  illustrates a cross-section of the waveguide connector in  FIG. 1A  along sectional line B-B; 
         FIG. 2  illustrates a cross-section of the waveguide connector in  FIG. 1A  along sectional line B-B in accordance with another embodiment described herein; 
         FIG. 3  illustrates a cross-section of the waveguide connector in  FIG. 1A  along sectional line B-B in accordance with another embodiment described herein; 
         FIG. 4A  illustrates a cross-section of an example waveguide connector in accordance with at least one embodiment described herein; 
         FIG. 4B  illustrates a cross-section of the waveguide connector of  FIG. 4A , including added peripheral members; 
         FIG. 4C  illustrates a cross-section of the waveguide connector of  FIGS. 4A and 4B , including added sacrificial material; 
         FIG. 4D  illustrates a cross-section of the waveguide connector of  FIGS. 4A-4C , including added top members; 
         FIG. 4E  illustrates a cross-section of the waveguide connector of  FIGS. 4A-4D , including additional layers; 
         FIG. 4F  illustrates a cross-section of the waveguide connector of  FIGS. 4A-4E , including an added top layer; 
         FIG. 4G  illustrates a cross-section of the waveguide connector of  FIGS. 4A-4F , with sacrificial material partially or completely removed, leaving behind cavities; 
         FIG. 4H  illustrates a cross-section of the waveguide connector of  FIGS. 4A-4G , with additional material added; 
         FIG. 5  illustrates a cross-section of an example waveguide connector in accordance with at least one other embodiment described herein; 
         FIG. 6  is a high-level flow diagram of an illustrative method of fabricating a waveguide connector in accordance with one embodiment described herein; 
         FIG. 7  is a high-level flow diagram of an illustrative method of partially or completely filling a waveguide with a dielectric material in accordance with one embodiment described herein; 
         FIG. 8A  illustrates a cross-section of an example waveguide connector in accordance with at least one embodiment described herein, including traces on a base layer; 
         FIG. 8B  illustrates a cross-section of the waveguide connector of  FIG. 8A , including and added layer; 
         FIG. 8C  illustrates a cross-section of the waveguide connector of  FIGS. 8A and 8B , including additional traces; 
         FIG. 8D  illustrates a cross-section of the waveguide connector of  FIGS. 8A-8C , including an additional layer; 
         FIG. 8E  illustrates a cross-section of the waveguide connector of  FIGS. 8A-8D , including an additional layer; 
         FIG. 8F  illustrates a cross-section of the waveguide connector of  FIGS. 8A-8E , with traces partially or completely removed, leaving behind cavities; 
         FIG. 8G  illustrates a cross-section of the waveguide connector of  FIGS. 8A-8F , with additional material added; 
         FIG. 9  illustrates a cross-section of an example waveguide connector in accordance with another embodiment described herein; 
         FIG. 10  is a high-level flow diagram of an illustrative method of fabricating a waveguide connector in accordance with one embodiment described herein; 
         FIG. 11  is a high-level flow diagram of an illustrative method of partially or completely filling a waveguide with a dielectric material in accordance with one embodiment described herein; 
         FIG. 12  illustrates a three-dimensional cutaway view of an example waveguide connector in accordance with at least one embodiment described herein; 
         FIG. 13  illustrates a three-dimensional cutaway view of another example waveguide connector in accordance with at least one embodiment described herein; 
         FIG. 14  illustrates a general three-dimensional cutaway view of another example waveguide connector in accordance with at least one embodiment described herein; 
         FIG. 15  illustrates a general three-dimensional view of a waveguide connector system in accordance with at least one embodiment described herein; 
     
    
    
     Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications and variations thereof will be apparent to those skilled in the art. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Generally, this disclosure provides apparatus and systems for coupling waveguides to a server package with a modular connector system, as well as methods for fabricating such a connector system. Such a system may be formed with connecting waveguides that rotate through a desired angle, which in turn may allow a server package to send a signal through a waveguide bundle in any given direction without bending waveguides of the bundle. 
     A power-competitive data transmission means that can support very high data rates over short to medium distances would be extremely advantageous. The systems and methods disclosed herein provide waveguide connector systems and methods that may facilitate the transmission of data between blade servers (“blades”) within a server rack or between collocated server racks using millimeter-waves (mm-waves) and sub-Terahertz (sub-THz) waves. For example, mm-waves are electromagnetic waves having frequencies from about 30 GHz to about 300 GHz, and sub-THz waves are electromagnetic waves having frequencies ranging from about 100 GHz to about 900 GHz. The waveguide connector systems disclosed herein may enable the coupling of one or more waveguide members to a package in a location proximate to the radio frequency (“RF”) launchers or antennas carried by the package. The systems and methods disclosed herein may facilitate the coupling of one or more waveguides to the packages either individually or grouped together using a modular connector or similar device. Put simply, one embodiment of the system disclosed herein may effectively serve as a modular “joint” or adaptive connector between a package output and a waveguide bundle. This is advantageous because it allows waveguide bundle connections between packages without bending the bundle itself and without particularly realigning the packages. For example, using one of the systems disclosed herein at each end of a waveguide bundle may advantageously allow a straight-line waveguide bundle to connect two different packages whose input/output ports are not facing each other, without moving the packages. 
     The systems and methods disclosed herein may further facilitate the fabrication of modular waveguide connector systems. More particularly, the introduction of a printed fabrication method may allow nonlinear waveguides to be constructed or implemented without bending. 
     The terms “horizontal” and “vertical” as used in any embodiment herein are not used as terms of limitation, but merely as relative terms to simplify descriptions of components of those embodiments. The terms may be substituted or interchanged with no impact on the intended meaning or scope of the description of any embodiment. For example, a component described as vertical may be horizontal if the system to which the component is attached is rotated through an angle of 90°. The terms “row” and “column” are similarly used herein as relative terms for simplification purposes only, and may be substituted or interchanged with no impact on intended meaning or scope. The terms “first” and “second” are similarly used herein as relative terms for simplification purposes only, and may be substituted or interchanged with no impact on intended meaning or scope. The terms “height,” “width” and “depth” are similarly used herein as relative terms for simplification purposes only, and may be substituted or interchanged with no impact on intended meaning or scope. The term “package” is used herein to describe a package substrate. The package may be any kind of package substrate including organic, plastic, ceramic, or silicon used for a semiconductor integrated circuit. 
     Some Figures include an XYZ compass to denote a 3-dimensional coordinate system. This is included and used for clarity and explanatory purposes only; the embodiments depicted are not intended to be limited by the inclusion or use of such a coordinate system. The labels or directions may be substituted or interchanged with no impact on intended meaning or scope. 
       FIG. 1A  illustrates a view  100 A of an example waveguide connector  110  in accordance with at least one embodiment described herein.  FIG. 1B  illustrates a cross-section  100 B of the waveguide connector  110  in  FIG. 1A  along sectional line B-B. 
     Turning to  FIG. 1A , a first end of a waveguide connector  110  may be operably coupled to waveguide bundle  130  and/or a second end of the waveguide connector  110  may be operably coupled to a package, such as package  151 . Package  151  may be any of a plurality of materials, such as organic materials (e.g., dielectric materials) sandwiched between metallic traces (e.g., copper). Waveguide connector  110  may include a housing  120  disposed about all or a portion of some or all of the one or more waveguides  112 A, . . . ,  112 N (collectively referred to as “waveguides”). Waveguide bundle  130  may contain one or more external waveguides  132 A, . . .  132 N (collectively referred to as “external waveguides”). Package  151  may contain one or more launchers or excitation elements such as outputs  156 A, . . . ,  156 N (collectively referred to as “package outputs”), capable of bidirectional or unidirectional communication with one or more external devices via a waveguide (such as one of external waveguides). Package outputs may also serve as package inputs at the same time, or at different times. 
     Waveguide connector  110  may be any of a plurality of dimensions. For example, waveguide connector  110  may have a height of about 1 centimeter (cm) or greater, a width of about 1 cm or greater and a depth of about 1 cm or greater. However, any or all of these dimensions may vary; waveguide connector  110  may have a height of about 1.5 cm or greater, a width of about 0.5 cm or greater and a depth of about 20 cm or greater. These dimensions allow the waveguide connector  110  to advantageously fit between blades in a server rack, thereby not requiring reconfiguration or repositioning of blades within the rack. 
     Housing  120  may be made of a plurality of materials, such as metal, plastic, a composite, etc. Housing  120  may be of a conductive or nonconductive material. Housing  120  may be attached, affixed, secured, or otherwise operably coupled to waveguide bundle  130  and/or package  151 . Housing  120  may partially or completely enclose each of the waveguides. 
     Each of the waveguides may be of any physical configuration, cross-section or geometry, such as straight, bent or curved. Each of the waveguides may be partially or fully contained within housing  120 . Each of the waveguides may have a first end and a second end, connected by walls. The walls of the waveguides may be made of any of a plurality of conductive materials, such as metals, polymers, composites, etc. In another embodiment, housing  120  may be made of a material suitable for providing all or a portion of one or more walls of some or all of the waveguides, allowing the waveguides to be fabricated without creating individual walls (in such an embodiment, the walls of each of the waveguides would instead simply be provided in whole or in part by the housing  120  itself). Each of waveguides the may be hollow, partially filled with a dielectric material, or fully filled with a dielectric material such as plastic, porcelain, glass, gaseous nitrogen, etc. In another embodiment, the waveguides may be left partially or completely hollow, using air or a vacuum as a dielectric. The dimensions of the waveguides may be any of a plurality of geometric configurations. For example, the waveguides may have a transverse cross-sectional geometry that is about 1 mm×2 mm or greater, about 3 mm×3 mm or greater, about 2 mm×0.5 mm or greater, etc. The cross-sectional dimensions of the waveguide may also vary with the frequency of operation and the dielectric properties of the waveguide filling. For example, a waveguide using air as a dielectric filling operating at a frequency of about 100 GigaHertz (GHz) may have a transverse cross-sectional geometry that is about 1 mm×about 2 mm, while a waveguide using air as a dielectric filling operating at a frequency of about 200 GHz may have a transverse cross-sectional geometry that is about 0.62 mm×about 1.2 mm. The length of the waveguides may be, for example, about 5 mm or greater, about 10 mm or greater, about 15 mm or greater, about 25 mm or greater, about 100 mm or greater, etc. The waveguides may all be of a similar length, or may have different lengths. “Similar” lengths, as used herein may include waveguides whose lengths differ by, for example, about 0.1 mm or less, about 2 mm or less, about 5 mm or less, about 10 mm or less, or by about 1% or less, by about 3% or less, by about 5% or less, etc. The waveguides may have a transverse cross-sectional geometry that is constant along their length, or may have a variable cross-sectional geometry. Some or all of the waveguides may have a transverse cross-sectional geometry different from other waveguides, or they may all have the same or similar transverse cross-sectional geometry. The possible cross-sectional geometries of the waveguides will be described in further detail below. 
     The waveguides may be operably coupled to external waveguides. This may be accomplished in any of a number of ways. For example, one end of a waveguide may terminate with a waveguide transition feature. The waveguide transition feature may contain one or more features  114 A, . . .  114 N (collectively referred to as “waveguide transition feature”), as depicted in  FIG. 1B . One end of an external waveguide may terminate in an external waveguide transition feature. The external waveguide transition feature may contain one or more features  134 A . . .  134 N (collectively referred to as “waveguide transition feature”). These transition features may be changes in the cross-sectional dimensions of either the waveguide or the external waveguide, and may be permanently attachable or detachably attachable to one another, allowing a waveguide to attach, be secured, or otherwise operably couple to a corresponding external waveguide. 
     In another embodiment, one of the waveguide transition feature or the external waveguide transition feature may be absent. If the waveguide transition feature is absent, then the external waveguide transition feature is capable of operably coupling to the waveguide itself. Similarly, if the external waveguide transition feature is absent, then the waveguide transition feature is capable of operably coupling to the corresponding external waveguide itself. In such an embodiment, waveguide transition feature may operably couple to the corresponding external waveguide using, for example, mechanical friction. In additional embodiments, transition features such as the waveguide transition feature and/or external waveguide transition feature may be capable of attaching to either a waveguide or another transition feature. The form of the transition features may vary and will be described in further detail below. 
     Similarly, waveguides may be operably coupleable to package outputs of package  151 . One end of a waveguide may terminate in a package output attachment feature  116 A, . . . ,  116 N (collectively referred to as “package output attachment feature”). In some embodiments, package output attachment feature is implemented as a transition feature, similar to the waveguide transition feature. Package output may attach directly to the waveguide without any package output attachment feature, as will be described in further detail below. Package output attachment feature(s) may be fabricated into package  151  during the manufacturing process of package  151 , or may be attached afterwards. 
     In some embodiments, waveguides may remain on the same plane, as depicted in  FIG. 1A . Each end of a waveguide (e.g.,  112 A) may be on the same plane as the corresponding end of the remaining waveguides (e.g.,  112 B, . . . ,  112 N). In other embodiments, some or all of waveguides may bend or curve in additional directions, which may result in some or all of waveguides being on different planes or even failing to be on any single plane. As a simple clarifying example, for any defined XYZ Cartesian coordinate system, if a waveguide is fabricated such that a first segment of the waveguide is parallel to the Y axis, a second segment that bends waveguide 90° to be parallel to the X axis, then after a straight third segment, a fourth segment that bends the waveguide another 90° to be parallel to the Z axis, then the waveguide will not fall within any single two-dimensional plane in the defined space XYZ. 
     A waveguide may be attached to both an external waveguide and a package output. This attachment may allow the signal from the package output to travel through, propagate through, or otherwise excite the waveguide and external waveguide. The package output may serve as an input, meaning this attachment may allow a signal from external waveguide to travel through, propagate through, or otherwise excite the waveguide and into the package input. Advantageously, the use of a waveguide may reduce or even eliminate signal degradation. 
     Waveguide connector  110  may be detachably attachable or permanently attachable to waveguide bundle  130 , as will be described in further detail below. Waveguide connector  110  may also be detachably attachable or permanently attachable to package  151 , as will be described in further detail below. 
       FIG. 1B  illustrates a cross-section  100 B of the waveguide connector  110  in  FIG. 1A  along sectional line B-B. Waveguides may be arranged along columns  140 A, . . . ,  140 N (hereinafter referred to as “columns”) or horizontal rows  150 A,  150 B, . . . ,  150 N (hereinafter referred to as “rows”). As seen in  FIG. 1B , waveguide connector  110  may contain a plurality of vertically stacked rows of waveguides. For example, waveguide  112 N, depicted in both  FIG. 1A  and  FIG. 1B , may be above waveguide  112 X, depicted in  FIG. 1B . Waveguides in a column are horizontally offset from waveguides in a different column by a horizontal offset  146 . Horizontal offset  146  may be, for example, about 10 μm or greater, about 50 μm or greater, about 0.5 mm or greater, about 1 mm or greater, about 1.5 mm or greater, about 2 mm or greater, about 5 mm or greater, about 10 mm or greater, etc. Waveguides in a row are vertically offset from waveguides of a different row by a vertical offset  152 . Vertical offset  152  may be, for example, about 10 μm or greater, about 50 μm or greater, about 0.5 mm or greater, about 1 mm or greater, about 1.5 mm or greater, about 2 mm or greater, about 5 mm or greater, about 10 mm or greater, etc. In some embodiments, waveguides may actually contact other waveguides (e.g., horizontal offset  146  and/or vertical offset  152  may be zero). Waveguide connector  110  may only have a single row of waveguides  150 A, . . .  150 X. In another embodiment, waveguide connector  110  may only contain a single column of waveguides  112 N, . . . ,  112 X. While  FIG. 1B  depicts waveguides arranged in a grid, rows may be also horizontally offset from other rows, as will be described in further detail below. 
       FIG. 2  illustrates a cross-section  200  of the waveguide connector  110  in  FIG. 1A  along sectional line B-B in accordance with another embodiment described herein. In this embodiment some or all rows of the waveguides may be staggered or offset from other rows. For example, the waveguides of row  150 B are not horizontally aligned with any waveguides of row  150 A. The leftmost waveguides of rows  150 B and  150 N are instead aligned in column  140 C, which is offset from column  140 A by staggered offset  148 . Staggered offset  148  may be, for example, about 0.25 mm or greater, about 0.5 mm or greater, about 1 mm or greater, about 1.5 mm or greater, about 2 mm or greater, about 5 mm or greater, about 10 mm or greater, etc. As depicted in  FIG. 2 , column  140 C may also be offset from column  140 B. Column  140 C may be offset from column  140 B by the same staggered offset  148  (placing column  140 C directly between columns  140 A and  140 B), or column  140 C may be offset from column  140 B by a different amount. Some rows of the waveguides may align with other rows. Each of the waveguides  112 N, . . .  112 X may be connected to a waveguide transition feature  114 N, . . .  114 X or to a package output attachment feature (not shown in  FIG. 2 ). 
       FIG. 3  illustrates a cross-section  300  of the waveguide connector  110  in  FIG. 1A  along sectional line B-B in accordance with another embodiment described herein. As shown in  FIG. 3 , some of the waveguides may have different cross-sectional geometries than other waveguides. For example, waveguide  112 A is depicted in  FIG. 3  with a triangular cross-sectional geometry, while waveguide  112 X has a circular cross-sectional geometry. Waveguides may also have different cross-sectional geometries from other waveguides contained within the same row. The cross-sectional geometry of each waveguide may be any polygonal shape. Dimensional notations of rows, columns, and offsets  152 ,  146 , and  148  have been retained in  FIG. 3  for simplicity. 
       FIGS. 4A-4H  illustrate cross-sections of an illustrative example of a waveguide connector in accordance with at least one embodiment described herein.  FIG. 4A  illustrates a base layer  410 . Base layer  410  may be made of a non-conductive substrate such as a ceramic, a polymer, a plastic, or a dielectric composite material. Dielectric composite materials suitable for base layer  410  include glass-reinforced or paper-reinforced epoxy resins using dielectrics such as polytetrafluoroethylene, Flame Retardant-4 (FR-4), Flame Retardant-1 (FR-1), Composite Epoxy Material-1 (CEM-1), Composite Epoxy Material-3 (CEM-3), phenolic paper, or various other materials known to those skilled in the art. Base layer  410  may have any physical configuration or geometry. For example, base layer  410  may be about 30 mm or greater×about 4 mm or greater×about 30 mm or greater, or about 20 mm or greater×about 3 mm or greater×about 100 mm or greater, etc. Base layer  410  may be formed using any of a variety of methods. For example, base layer  410  may be formed using printing, 3D-printing, plating, photolithographic deposition, etc. Base layer  410  may have one or more grooves  414 A, . . . ,  414 N (collectively referred to as “grooves”). Grooves may be evenly spaced from each other, or may be spaced inconsistently. Grooves may be any of a plurality of sizes. For example, grooves may be the same or larger than the waveguides. Grooves may be straight, curved, or bent. Grooves may be any polygonal shape. Grooves may be formed simply by fabricating base layer  410  “around” them (i.e., neglecting to fill in grooves), or may be formed subtractively (i.e., by removing material from base layer  410  to leave grooves). 
       FIG. 4B  illustrates a cross-section of the waveguide connector of  FIG. 4A , including added peripheral members  416 A, . . . ,  416 N (collectively referred to as “peripheral members”). Peripheral members may be added to the inside of grooves. Peripheral members may be made of any one of a variety of conductive materials, including metals (copper, silver, gold, etc.) semiconductors, etc. Peripheral members may be fabricated by any one of a variety of methods, including plating, depositing, thermal oxidation, lamination, photolithographic deposition, electroplating, electroless plating, 3D printing, etc. Peripheral members may have any thickness. For example, peripheral members may be about 1 μm or greater, about 20 μm or greater, about 50 μm or greater, about 100 μm or greater, about 150 μm or greater, about 250 μm or greater, etc. 
       FIG. 4C  illustrates a cross-section of the waveguide connector of  FIGS. 4A and 4B , including added sacrificial material  422 A, . . . ,  422 N (collectively referred to as “sacrificial material”). Metallized grooves  414 A may be partially or completely filled with sacrificial material. The sacrificial material may be a dielectric material, metal, plastic, composite, etc. In some embodiments, the sacrificial material is a placeholder material and may be partially or completely removed later, as will be described below. In other embodiments, sacrificial material is not removed, and may function as a component of one or more of the waveguides. 
       FIG. 4D  illustrates a cross-section of the waveguide connector of  FIGS. 4A-4C , including added top members  418 A, . . . ,  418 N (collectively referred to as “top members”). Top members may be added on top of sacrificial material and peripheral members Top members may be made of any one of a variety of conductive materials, including metals (copper, silver, gold, etc.) semiconductors, etc. Top members may be fabricated by any one of a variety of methods, including plating, depositing, thermal oxidation, lamination, photolithographic deposition, electroplating, electroless plating, 3D printing, etc. Top members may combine with peripheral members to partially or fully enclose sacrificial material. As top members are added, they may combine with peripheral members to form the walls of the waveguides. Top members may be similar in size or thickness to peripheral members (e.g., within +/−10 μm). 
       FIG. 4E  illustrates a cross-section of the waveguide connector of  FIGS. 4A-4D , including additional layers  426 A, . . . ,  426 N (collectively referred to as “additional layers”). Additional layers may be added to base layer  410 . Each of the additional layers may be formed in a manner similar to that depicted in  FIGS. 4A-4D . Additional layers may partially or completely enclose the top members  418 X of preceding layers. In another embodiment, no additional layers are added. 
       FIG. 4F  illustrates a cross-section of the waveguide connector of  FIGS. 4A-4E , including an added top layer  430 . Top layer  430  may be added to the uppermost (or topmost) layer of the waveguide connector. The topmost layer may be the last additional layer added, or if no additional layers have been added base layer  410  is also the topmost layer. Top layer  430  may partially or completely enclose top members  418  and/or waveguides of the topmost layer. 
       FIG. 4G  illustrates a cross-section of the waveguide connector of  FIGS. 4A-4F , with sacrificial material (i.e.  422 A,  422 N, . . .  422 X) in  FIG. 4F  partially or completely removed, leaving behind cavities  434 A,  434 N, . . . ,  434 X (collectively referred to as “cavities”). The exact method of removal may depend on the specific makeup of sacrificial material. For example, if sacrificial material is made of a metal, removal may be accomplished chemically, mechanically, electrochemically, thermally, or combinations thereof. However, for example, if sacrificial material is a plastic, removal may preferentially be accomplished chemically, but may also be accomplished mechanically, electrochemically, thermally, or combinations thereof. Various other methods of removal may be feasible, as known by those skilled in the art. 
     In some embodiments, the waveguides may be left partially or completely hollow, and fabrication of the waveguides may be considered complete at the point depicted in  FIG. 4G . In other embodiments, the waveguides may be filled with a material, as will be described in further detail below. In other embodiments, sacrificial material may be a dielectric material with an acceptable dielectric constant and loss tangent and is not removed. “Acceptable” dielectric constants may include, for example, dielectric constants of about 10 or less. The range of acceptable loss tangents may depend on the waveguide. For “internal” waveguides such as waveguides  112 A, . . . ,  112 N, acceptable loss tangents include, for example, loss tangents about 0.1 or less. External waveguides may generally have stricter tolerances for loss tangents, e.g. may require a loss tangent of about 0.02 or less. 
       FIG. 4H  illustrates a cross-section of the waveguide connector of  FIGS. 4A-4G , with additional material  440 A,  440 N, . . . ,  440 X (collectively referred to as “additional material”). Additional material may be a dielectric such as a ceramic, a polymer, a plastic, or a dielectric composite material. The filling may be performed via depositing, plating, printing, etc. 
       FIG. 5  illustrates a cross-section  500  of an example waveguide connector in accordance with at least one other embodiment described herein. Instead of adding additional layers directly on top of each other or base layer  410 , additional layers may be added in a “staggered” configuration, as seen in  FIG. 5 . Thus, rows of waveguides may be offset from one another. For example, waveguide  112 N may be offset from waveguide  112 X. In some embodiments, no waveguides may be vertically or horizontally aligned with any others. In other embodiments, some waveguides may be vertically aligned with others, as in a column. As depicted in  FIG. 5 , the waveguides may be filled with additional material  540 A,  540 N,  540 R, . . .  540 X, as described above (i.e.  440 A,  440 N, . . . ,  440 X in  FIG. 4H ). In some embodiments, the waveguides may be left partially or completely hollow. 
       FIG. 6  is a high-level flow diagram of an illustrative method  600  of fabricating a waveguide connector in accordance with one embodiment described herein. Generally, method  600  involves forming a base layer with grooves, preparing those grooves to function as waveguides, and optionally adding additional similar layers of waveguides. Method  600  may generally result in the various stages of fabrication of a waveguide connector depicted in  FIGS. 4A-4H . 
     At step  610 , a process of manufacturing a waveguide connector is initiated or started. At step  612 , a base layer (such as base layer  410 ) is formed. Base layer  410  may be fabricated through a variety of means, including subtractive processes, additive processes, semi-additive processes, 3D printing, plating, etc. In this embodiment, step  612  further entails forming base layer  410  with a plurality of grooves (such as grooves). Grooves may be formed simply by fabricating base layer  410  “around” them (i.e., neglecting to fill in grooves), or may be formed subtractively (i.e., by removing material from base layer  410  to leave grooves). 
     At step  614 , walls (such as peripheral members) are formed on the inner surfaces of grooves. As described above, peripheral members may be fabricated by any one of a variety of methods, including plating, depositing, thermal oxidation, lamination, photolithographic deposition, electroplating, electroless plating, etc. 
     At step  616 , grooves are filled. Grooves may be filled with a sacrificial dielectric material (such as sacrificial material). The filling may be performed via depositing, plating, printing, etc. 
     At step  618 , top walls (such as top members) are added on top of sacrificial material. Sacrificial material may be partially or completely enclosed at this point by peripheral members and top members. Top members may be formed in the same or a similar manner as peripheral members, or may be formed using a different one of the possible methods of forming peripheral members. For example, even if peripheral members are formed using photolithographic deposition, top members may be formed using 3D-printing. 
     At step  620 , a determination is made of whether one or more additional rows (such as rows) of waveguides (such as the waveguides) are desired. If any additional rows are desired (i.e. Yes), then method  600  may further include repeating steps  614 ,  616 ,  618 ,  620 , and  622  to form an additional layer at step  622  (such as additional layers), resulting in an additional row of waveguides. Note that the row of the waveguides of an additional layer may be offset from the previous row, as depicted in  FIG. 5 . If at step  620  no additional rows are desired (i.e. No), then at step  624 , a top layer (such as top layer  430 ) may be formed above the uppermost layer (which may be base layer  410  or one of additional layers). 
     At step  626 , the filling is removed. This filling may be sacrificial material. As discussed above, sacrificial material may be accomplished, for example, chemically, mechanically, electrochemically, thermally, or using combinations thereof. At step  640 , the process is ended. 
       FIG. 7  is a high-level flow diagram of an illustrative method  700  of partially or completely filling a waveguide (such as one of waveguides) with a dielectric material (such as additional material  440 A,  440 N, . . . ,  440 X). At step  710 , a process of filling a waveguide is initiated or started. At step  730 , cavities (such as cavities  434 ) are filled with another or alternate material, such as additional material  440 A,  440 N, . . . ,  440 X. This filling may be performed via depositing, plating, printing, etc. At step  740 , the process is ended. 
       FIGS. 8A-8G  illustrate cross-sections of an example waveguide connector in accordance with at least one embodiment described herein.  FIG. 8A  illustrates a cross-section of an example waveguide connector in accordance with at least one embodiment described herein, including traces  822 A, . . . ,  822 N (collectively referred to as “traces”) on a base layer  816 . Base layer  816  may be made of a metal, or any other conductive material. Base layer  816  may be fabricated via plating, depositing, 3D printing, etc. Base layer  816  may have any physical configuration or geometry. For example, base layer  816  may be about 30 mm or greater×about 4 mm or greater×about 30 mm or greater, or about 20 mm or greater×about 3 mm or greater×about 100 mm or greater, etc. Traces may be sacrificial members made of a sacrificial material, including the possible materials of sacrificial material (including a dielectric, a metal, a dielectric-coated metal, a plastic, a composite material, etc.), and may be removed later, as will be described in detail below. Traces may be straight, curved, or bent. Traces may be added to base layer  816  in any of a variety of ways, including printing, 3D-printing, depositing, attaching, plating, etc. Traces may have a cross-sectional geometry (as seen in  FIG. 8A ) of any polygonal shape. Traces may be of any size in any dimension, such as about 0.5 mm or greater×about 1 mm or greater, about 1 mm or greater×about 1 mm or greater, about 2 mm or greater×about 0.5 mm or greater, etc. 
       FIG. 8B  illustrates a cross-section of the waveguide connector of  FIG. 8A , including an added layer  818 A. Layer  818 A may be added on top of base layer  816 , and may partially or completely enclose traces  822 A, . . . ,  822 N. 
       FIG. 8C  illustrates a cross-section of the waveguide connector of  FIGS. 8A and 8B , including additional traces (including trace  822 R). These additional traces may be added on top of layer  818 A. The traces of the row including trace  822 R may be aligned with the traces below them, such as along columns, or they may be offset or staggered, as will be discussed in further detail below. The traces added on top of layer  818 A may be added using substantially the same method(s) described above. Traces may be aligned along rows, such as rows, and may be horizontally offset from each other by horizontal offset  146 . If traces are staggered, they may be horizontally offset from traces of a different row by a different offset value, such as staggered offset  148  in  FIG. 9 , as will be described in further detail below. 
       FIG. 8D  illustrates a cross-section of the waveguide connector of  FIGS. 8A-8C , including an additional layer  818 N. Layer  818 N may partially or completely enclose trace  822 R (not shown) and other traces on the same row. Layer  818 N may be made of the same materials and may be formed in the same way as layer  818 A. 
       FIG. 8E  illustrates a cross-section of the waveguide connector of  FIGS. 8A-8D , including an additional layer  818 X having additional traces  822 X. Layer  818 X which may be added using the operations depicted in  FIGS. 8C and 8D . In another embodiment, no layers beyond  818 A are added. In another embodiment, traces are made of a dielectric material suitable for waveguides, and are therefore not removed. 
       FIG. 8F  illustrates a cross-section of the waveguide connector of  FIGS. 8A-8E , with traces partially or completely removed, leaving behind cavities  834 A,  834 N,  834 R, and  834 X (collectively referred to as “cavities”). The exact method of removal may depend on the specific makeup of traces. For example, if traces are made of a metal, removal may be accomplished chemically, mechanically, electrochemically, thermally, or using combinations thereof. As a different example, if traces are a plastic, removal may be accomplished preferably chemically, but may still be accomplished mechanically, electrochemically, thermally, or using combinations thereof. Various other methods of removal may be feasible, as known by those skilled in the art. In some embodiments, the waveguides may be left partially or completely hollow, as in  FIG. 8F . In other embodiments, the waveguides may be filled with another material. In still other embodiments, traces may be a dielectric material and are not removed. 
       FIG. 8G  illustrates a cross-section of the waveguide connector of  FIGS. 8A-8F , with additional material  440 A,  440 N,  440 R, . . .  440 X added. As described above, additional material may be partially or completely filled into the waveguides  112 A,  112 N,  112 R, . . .  112 X via a plurality of methods. For example, the waveguides may be partially or completely filled with additional material via depositing, plating, printing, etc. as shown in  FIG. 4H . 
       FIG. 9  illustrates a cross-section  900  of an example waveguide connector in accordance with another embodiment described herein. Instead of adding additional layers  818 N, . . . ,  818 X so that the waveguides are directly on top of each other or the waveguides of layer  818 A as in  FIGS. 8A-8G , additional layers may be added in a “staggered” configuration, as seen in  FIG. 9 . Thus, rows  150 A and  150 B of the waveguides may be added such that columns  140 A,  140 B and  140 C of the waveguides are horizontally offset from one another. For example, waveguide  112 R may be offset from waveguides  112 N and  112 X. In some embodiments, no waveguides may be vertically or horizontally aligned with any others. In other embodiments, some waveguides may be vertically aligned with others. As depicted in  FIG. 9 , the waveguides may be partially or completely filled with additional material  440 A,  440 N,  440 R, . . .  440 X, as discussed above. The waveguides may be left partially or completely hollow. 
       FIG. 10  is a high-level flow diagram of an illustrative method  1000  of fabricating a waveguide connector in accordance with one embodiment described herein. Generally, method  1000  involves preparing a base plate with formed traces, adding any desired additional layers of plate and traces, and removing the traces. Method  1000  may generally result in the various stages of fabrication of a waveguide connector depicted in  FIGS. 8A-8G . 
     At step  1010 , a process of manufacturing a waveguide connector is initiated or started. At step  1012 , a base plate (such as base layer  816 , not shown) is formed. Base layer  816  (not shown) may be fabricated through a variety of means, including subtractive processes, additive processes, semi-additive processes, 3D printing, plating, etc. as shown in  FIG. 8A . 
     At step  1014 , traces (such as traces  822 A, . . . ,  822 N) are formed on the surface of the plate. As discussed above, traces may be added to base layer  816  (not shown) in any of a variety of ways, including printing, 3D-printing, depositing, attaching, plating, etc. as shown in FIG.  8 A. At step  1016 , additional plating (such as layer  818 A) is formed around traces. Additional layer  818 A may be added in any of the ways base layer  816  (not shown) is made, including subtractive processes, additive processes, semi-additive processes, 3D printing, plating, etc. as shown in  FIG. 8B . 
     At step  1020 , a determination is made of whether or not to add additional rows (such as rows of the waveguides). If additional rows are desired (i.e. Yes), further operations may include forming additional traces at step  1022  (i.e.  822 A, . . . ,  822 N, not shown) on the surface of the uppermost plate (such as layer  818 A, not shown, or the most recently added additional layer) and proceeding to step  1016 . If no additional rows are desired (i.e. No) at step  1020 , at step  1026  traces are removed. At step  1040 , the process is ended as shown in  FIGS. 8C-8G . 
       FIG. 11  is a high-level flow diagram of an illustrative method  1100  of partially or completely filling a waveguide (such as one of the waveguides as shown in  FIG. 1A ) with a dielectric material (such as additional material  440 A,  440 N, . . . ,  440 X as shown in  FIG. 4H ). At step  1110 , a process of filling a waveguide is initiated or started. At step  1130 , cavities (such as cavities  834 A,  834 N,  834 R, and  834 X as shown in  FIG. 8F ) are filled with another or alternate material, such as additional material  440 A,  440 N, . . . ,  440 X. This filling may be performed via depositing, plating, printing, etc. At step  1140 , the process is ended. 
       FIG. 12  illustrates a three-dimensional cutaway view  1200  of an example waveguide connector  110  in accordance with at least one embodiment described herein. Waveguides  112 A, . . .  112 X may be operably coupled to waveguide bundle  130  and/or may be operably coupled to package  151 . Note that none of the waveguides depicted in  FIG. 12  move in the positive or negative Y direction. This means that in this embodiment, multiple waveguides on the same X-Z plane may not have the same or similar length. 
       FIG. 12  depicts five waveguides for ease of understanding. Other embodiments may have more or fewer waveguides. Further, as mentioned above, the waveguides may be partially or fully contained within housing  120 , which has been cut away in  FIG. 12  for simplicity. The boundaries of housing  120  are represented in  FIG. 8  by dashed lines. While housing  120  is depicted as a “pie shape” in  FIG. 12 , housing  120  may be any of a plurality of shapes, including a cube, a partial sphere, or any other polygonal shape. The waveguides may be curved, allowing a signal to propagate from package  151  to waveguide bundle  130  (or from waveguide bundle  130  to package  151 ) without bending either package  151  or waveguide bundle  130 . The waveguides may be partially or completely hollow or partially or completely filled with a material. The waveguides may have waveguide transition features as shown in  FIG. 1  A, which are not shown for simplicity. The dimensions of package  151  may vary. For example, package may be about 20 mm or greater×about 20 mm or greater×about 0.5 mm or greater. The dimensions of waveguide bundle  130  may also vary. For example, waveguide bundle  130  may be about 2 meters (m) or greater×about 10 mm or greater×about 10 mm or greater. A 10 mm×10 mm waveguide connector  110  may contain, for example, 16 waveguides in a 4×4 array. 
       FIG. 13  illustrates a three-dimensional cutaway view  1300  of another example waveguide connector  110  in accordance with at least one embodiment described herein. Waveguides  112 A, . . . ,  112 N may be bent in more than one dimension. The waveguides may be of equal length. 
     For example, waveguide  112 A remains on the X-Z plane, but extends from the farthest corner (i.e., in the negative X direction) of package  151  to the farthest corner (i.e., in the positive Z direction) of waveguide bundle  130  as shown in  FIG. 13 . However, in this embodiment, waveguide  112 N extends from the closest corner (i.e., in the positive X direction) of the package. In some embodiments, such as that depicted in  FIG. 12 , all of the waveguides connect to a point on the same X-Z plane as they originate, and therefore waveguide  112 N would have to connect to the closest corner (i.e., in the negative Z direction) of waveguide bundle  130  (for example, see waveguide  112 X as depicted in  FIG. 12 ). However, such a waveguide would be substantially shorter than, for example, waveguide  112 A (as depicted in either  FIG. 12  or  FIG. 13 ). As signals carried or transported through waveguides may degrade depending on the length of a waveguide, it is advantageous to have all waveguides remain the same or similar length. 
     Thus, in the embodiment depicted in  FIG. 13 , waveguide  112 N extends from the closest corner of the package  151  to the farthest corner (i.e., in the positive Z direction AND the negative Y direction) of the waveguide bundle  130 . Extending in the Y direction as well advantageously allows waveguide  112 N to have a length that is the same or similar to waveguide  112 A (e.g., within ±50 μm). 
     As depicted in  FIG. 13 , the waveguides may each have one end in a horizontal alignment, but bend such that the other end of each of the waveguides is in a vertical alignment. This may allow waveguides to propagate a signal between waveguide bundle  130  and package  151  without bending waveguide bundle  130  or package  151 , and while advantageously keeping waveguides at a constant or similar length. Keeping waveguides at a constant or similar length is desirable because it may promote signal cohesion and alleviate dispersion. Because the length of a waveguide may impact the transmitted signal (e.g. impact their phase component), a waveguide connector such as one consistent with the present disclosure may be more effective or desirable if it keeps all of the waveguides at a constant or similar length. In other embodiments, waveguides may be in other “transplanar” arrangements allowing waveguides to be of a constant or similar length while bending. 
     Note that like  FIG. 12 ,  FIG. 13  also depicts five waveguides for ease of understanding. Other embodiments may have more or fewer waveguides. Further, the waveguides may be partially or fully contained within housing  120 , which has been cut away in  FIG. 13  for clarity. The boundaries of housing  120  are represented in  FIG. 13  by dashed lines. 
       FIG. 14  illustrates a general three-dimensional cutaway view  1400  of another example waveguide connector  110  in accordance with at least one embodiment described herein. In this embodiment, connector  110  comprises housing  120  and waveguides  112 A, . . .  112 N. Only the first end of the waveguides is depicted in  FIG. 14 ; the second end of the waveguides may be along the bottom face (where the bottom face is parallel to the X-Y plane at minimum Z) of housing  120 . Note that in  FIG. 14 , the waveguides are depicted in a staggered layout, which is mentioned above as one possible embodiment. The waveguide may be in a grid layout, or any other feasible layout (e.g., arranged along a single line, in a circle, in a plurality of concentric circles, in a “cross” or X layout, etc.). The waveguides are also depicted as having a rectangular cross-sectional geometry, but as discussed above (e.g.,  FIG. 3 ), the waveguides may have any of a plurality of cross-sectional geometries. As discussed above (e.g.,  FIG. 12 ), housing  120  is depicted as having a “pie-slice” shape, but may have any of a plurality of shapes. A waveguide connector  110  may have one or more housing attachment features  1482 , as depicted in  FIG. 14 . Housing attachment features  1482  may allow the waveguide connector  110  to attach, secure, or otherwise operable couple to either a waveguide bundle  130  (not shown) or a package  151  (not shown). Housing attachment features  1482  may be any of a variety of forms and utilize any of a variety of means to secure waveguide connector  110  to waveguide bundle  130  or package  151 . For example, housing attachment features  1482  may utilize mechanical features (e.g., screws, bolts, ratchets, binding, snaps, etc.), chemical features (e.g., adhesives, bonding agents, etc.) thermal features (e.g., soldering, welding, etc.), or electromagnetic features (e.g., magnets, electrical fields, etc.).  FIG. 14  also depicts waveguide attachment features  1484  alongside some of the waveguides. Note that not all waveguides are depicted in  FIG. 14  as having waveguide attachment features  1484  for simplicity. In other embodiments, none, some, or all of the waveguides may have waveguide attachment features  1484 . Waveguide attachment features  1484  allow the waveguides to be secured, attached, connected, or otherwise operably coupled to external waveguides (not shown) or package outputs (not shown). Waveguide attachment features  1484  may utilize any of the means described for housing attachment features  1482 , such as mechanical features, chemical features, thermal features, or electromagnetic features. Waveguide attachment features  1484  are depicted in  FIG. 14  as being external to housing  120 . However, in other embodiments, waveguide attachment features  1484  may be partially or fully contained within housing  120 . 
       FIG. 15  illustrates a general three-dimensional view (i.e. X-Y-Z directions)  1500  of a waveguide connector system in accordance with at least one embodiment described herein. Here, two connectors  110 A and  110 B may be operably coupled to packages  151 A and  151 B respectively. Connectors  110 A and  110 B may also be operably coupled to waveguide bundle  130 . Waveguide bundle  130  may use a variety of external waveguides such as  132 A to operably connect connector  110 A to connector  110 B. This connection may allow a signal generated in package  151 A to travel, propagate, or be transmitted through the waveguides (not shown) within the housing  120 A of connector  110 , into and through external waveguides, into and through the waveguides (not shown) within the housing  120 B of connector  110 B into package  151 B. Advantageously, such a signal propagation may be performed without bending package  151 A, waveguide bundle  130  or package  151 B. 
     The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications are possible within the scope of the claims. Accordingly, the claims are intended to cover all such equivalents.