Glass-based photonic bridge with integrated waveguides

Abstract

Devices, methods, and assemblies are provided that include glass-based photonic bridges that each defines first and second surfaces and includes an optical waveguide within the first surface extending from a first portion to a second portion of the glass-based photonic bridge. The first surface is attachable to a first photonic circuit such that the first portion and the optical waveguide align with the first photonic circuit and optical signals are able to transfer from the first photonic circuit to the optical waveguide. The first surface is also attachable to a second photonic circuit such that the second portion and the optical waveguide align with the second photonic circuit and optical signals are able to transfer from the optical waveguide to the second photonic circuit. The optical waveguide serves as an optical connection between the first photonic circuit and the second photonic circuit.

Description

GLASS-BASED PHOTONIC BRIDGE WITH INTEGRATED WAVEGUIDESPRIORITY APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Application Serial No. 63 / 571,190 filed on March 28, 2024, the content of which is relied upon and incorporated herein by reference in its entirety.FIELD

[0002] Example embodiments of the present disclosure generally relate to glass-based photonic bridges and, more particularly to, glass-based photonic bridges with optical waveguides configured to connect photonic circuits.BACKGROUND

[0003] Currently, fiber optical interconnects between two photonic integrated circuits (PIC) are realized via optical fibers. Known limitations of optical interconnects occur when a waveguide pitch is limited by fiber diameter. In addition, limitations occur when fiber termination takes up space, which requires a minimum length between PICs. Another known limitation occurs when tolerances of assemblies negatively impact connection losses.

[0004] For future systems, where optical interconnects are becoming shorter and higher density, use of optical fibers present difficulties for being easily scalable. Accordingly, new optical interconnect solutions are needed, particularly in the area of chip-to-chip communication and photonic multi-chip-modules (also referred to as “photonic MCM”).

[0005] Current solutions have high packaging complexity, such as due to having a combined mating process of optical and electrical connections. Further, in current solutions, electrical and optical connections are located on different physical planes, which causes a small tolerance window for process and material variations.

[0006] Improvements in the foregoing are desired.BRIEF SUMMARY

[0007] Some example embodiments of the present disclosure include glass-based photonic bridges that are configured to interconnect photonic circuits, which are configured to be connected to a substrate via electrical connection material such as solder balls, bumps, and / or copper pillars. Such glass-based photonic bridges include waveguide(s) for opticalinterconnection between photonic integrated circuits (PICs) (or dies). This enables electronic packaging techniques that do not require advanced features at a PIC (or die), such as small pitch through silica vias (TSVs). Further, such glass-based photonic bridges decouple optical and electrical connection processes.

[0008] Various glass-based photonic bridges disclosed herein are a thin component for potential use as an embedded solution. In some embodiments, the glass-based photonic bridge can be implemented by wafer bonding. Moreover, using an ultra-thin glass substrate including waveguides can enable mass production assembly technologies like wafer balling and flip chip, without the requirement of high density TSVs at a PIC level. In some embodiments, the glassbased photonic bridges are flexible so as to still provide high quality optical signal transfer between non-horizontally aligned PICs.

[0009] Some example embodiments include a glass-based photonic bridge having an optical waveguide extending between a first portion and a second portion of the glass-based photonic bridge. A first surface of the glass-based photonic bridge may be attached to a first photonic circuit such that the first portion and the optical waveguide align with the first photonic circuit such that optical signals are able to transfer from the first photonic circuit to the optical waveguide, and the first surface may be attached to a second photonic circuit such that the second portion and the optical waveguide align with the second photonic circuit such that optical signals are able to transfer from the optical waveguide to the second photonic circuit. The optical waveguide within the first surface may serve as an optical connection between the first photonic circuit and the second photonic circuit.

[0010] In an example embodiment, a glass-based photonic bridge is provided. The glassbased photonic bridge includes a first surface, a second surface opposite the first surface, and an optical waveguide within the first surface extending from a first portion of the glass-based photonic bridge to a second portion of the glass-based photonic bridge. The first surface is configured to be attachable to a first photonic circuit such that the first portion and the optical waveguide align with the first photonic circuit such that optical signals are able to transfer from the first photonic circuit to the optical waveguide, and the first surface is further configured to be attachable to a second photonic circuit such that the second portion and the optical waveguide align with the second photonic circuit such that optical signals are able to transfer from theoptical waveguide to the second photonic circuit. The optical waveguide within the first surface serves as an optical connection between the first photonic circuit and the second photonic circuit.

[0011] In some embodiments, the first photonic circuit and the second photonic circuit may be adjacent to a substrate, and an electrical connection material may be positioned between the first photonic circuit and the substrate and between the second photonic circuit and the substrate.

[0012] In some embodiments, the glass-based photonic bridge may be adjacent to the substrate.

[0013] In some embodiments, a surface of the substrate may define an indented portion, and the glass-based photonic bridge may be positioned at least partially within the indented portion when the electrical connection material is positioned for electrical connection between the first photonic circuit and the substrate and between the second photonic circuit and the substrate.

[0014] In some embodiments, a first thickness of the glass-based photonic bridge extending above the substrate may equal a second thickness of the electrical connection material.

[0015] In some embodiments, the substrate may be electrically connected to second sides of the first photonic circuit and the second photonic circuit that are opposite first sides of the first photonic circuit and the second photonic circuit that are connected to the glass-based photonic bridge.

[0016] In some embodiments, the electrical connection material may include solder balls.

[0017] In some embodiments, the solder balls may have a diameter that is one tenth of a micrometer.

[0018] In some embodiments, the electrical connection material may include one or more bumps or copper pillars.

[0019] In some embodiments, the glass-based photonic bridge may be embedded in a substrate.

[0020] In some embodiments, a thickness of the glass-based photonic bridge may be between 30 microns and 200 microns.

[0021] In some embodiments, a thickness of the glass-based photonic bridge may be between 50 microns and 100 microns.

[0022] In some embodiments, a thickness of the glass-based photonic bridge may be 50 microns.

[0023] In some embodiments, the glass-based photonic bridge may be polished to a desired thickness at least one of during or after a packaging process.

[0024] In some embodiments, the glass-based photonic bridge may be substantially flexible.

[0025] In some embodiments, the glass-based photonic bridge may include at least two optical waveguides.

[0026] In some embodiments, the first photonic circuit may include at least one first optical waveguide, and the second photonic circuit may include at least one second optical waveguide.

[0027] In some embodiments, an attachment of the glass-based photonic bridge to the first photonic circuit and the second photonic circuit may be configured such that the first photonic circuit is substantially and horizontally aligned with the second photonic circuit.

[0028] In some embodiments, an attachment of the glass-based photonic bridge to the first photonic circuit and the second photonic circuit may be configured such that the first photonic circuit is not horizontally aligned with the second photonic circuit.

[0029] In another example embodiment, a method of packaging a glass-based photonic bridge is provided. The method includes providing the glass-based photonic bridge, and the glass-based photonic bridge includes a first surface, a second surface opposite the first surface, and an optical waveguide within the first surface extending from a first portion of the glass-based photonic bridge to a second portion of the glass-based photonic bridge. The method also includes attaching the first surface to a first photonic circuit such that the first portion and the optical waveguide align with the first photonic circuit such that optical signals are able to transfer from the first photonic circuit to the optical waveguide and attaching the first surface to a second photonic circuit such that the second portion and the optical waveguide align with the second photonic circuit such that optical signals are able to transfer from the optical waveguide to the second photonic circuit. The optical waveguide within the first surface serves as an optical connection between the first photonic circuit and the second photonic circuit.

[0030] In some embodiments, the method may further include positioning the first photonic circuit and the second photonic circuit adjacent to a substrate and positioning an electrical connection material between the first photonic circuit and the substrate and between the second photonic circuit and the substrate.

[0031] In some embodiments, the glass-based photonic bridge may be adjacent to the substrate.

[0032] In some embodiments, the substrate may be electrically connected to second sides of the first photonic circuit and the second photonic circuit that are opposite first sides of the first photonic circuit and the second photonic circuit that are connected to the glass-based photonic bridge.

[0033] In some embodiments, the method may further include thinning the glass-based photonic bridge by polishing or etching.

[0034] In some embodiments, the method may further include attaching fiber connector receptacles at edges of the glass-based photonic bridge.

[0035] In another example embodiment, a glass-based photonic bridge assembly is provided. The glass-based photonic bridge assembly includes a glass-based photonic bridge, and the glassbased photonic bridge includes a first surface, a second surface opposite the first surface, and an optical waveguide within the first surface extending from a first portion of the glass-based photonic bridge to a second portion of the glass-based photonic bridge. The glass-based photonic bridge assembly also includes a first photonic circuit attached to the first surface of the glassbased photonic bridge such that the first portion and the optical waveguide align with the first photonic circuit such that optical signals are able to transfer from the first photonic circuit to the optical waveguide, a second photonic circuit attached to the first surface of the glass-based photonic bridge such that the second portion and the optical waveguide align with the second photonic circuit such that optical signals are able to transfer from the optical waveguide to the second photonic circuit, and a substrate connected to the first photonic circuit and the second photonic circuit by way of an electrical connection material disposed between the substrate and each of the first photonic circuit and the second photonic circuit. The optical waveguide within the first surface serves as an optical connection between the first photonic circuit and the second photonic circuit.

[0036] In some embodiments, the glass-based photonic bridge may be adjacent to the substrate.

[0037] In some embodiments, the glass-based photonic bridge may be opposite the substrate relative to the first photonic circuit and the second photonic circuit.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0038] Having thus described the disclosure in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0039] FIG. 1A illustrates a cross-sectional view of an example glass-based photonic bridge connected to a first photonic circuit and a second photonic circuit, while being adjacent a substrate, in accordance with some embodiments disclosed herein;

[0040] FIG. IB illustrates a cross-sectional view of the example glass-based photonic bridge of FIG. 1A connected to the first photonic circuit and the second photonic circuit, while being adjacent a substrate with an indented portion, in accordance with some embodiments disclosed herein;

[0041] FIG. 2A illustrates a cross-sectional view of an example glass-based photonic bridge connected to a first photonic circuit and a second photonic circuit, while being opposite a substrate relative the first photonic circuit and the second photonic circuit, in accordance with some embodiments disclosed herein;

[0042] FIG. 2B illustrates a cross-sectional view of an example glass-based photonic bridge connected to a first photonic circuit and a second photonic circuit with the glass-based photonic bridge having flexibility across an uneven profile defined by the first photonic circuit and the second photonic circuit being non-horizontally aligned, in accordance with some embodiments disclosed herein;

[0043] FIGs. 3A-3D illustrate an example process of packaging a glass-based photonic bridge in which the glass-based photonic bridge is bonded to a first photonic circuit and a second photonic circuit, in accordance with some embodiments disclosed herein;

[0044] FIGs. 4A-4B show example flowcharts of first and second approaches for executing example packaging processes, such as the process illustrated in FIGs. 3A-3D, in accordance with some embodiments disclosed herein; and

[0045] FIG. 5 is an example flowchart of a method of packaging a glass-based photonic bridge, in accordance with some embodiments disclosed herein.DETAILED DESCRIPTION

[0046] Some example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all example embodiments areshown. Indeed, the examples described and pictured herein should not be construed as being limiting as to the scope, applicability or configuration of the present disclosure. Rather, these example embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout.

[0047] FIG. 1A schematically illustrates an exemplary embodiment of a photonic bridge assembly 100, including a substantially thin glass substrate incorporated into a glass-based photonic bridge 110 embedded to or assembled with an organic substrate 160 (e.g., an organic printed circuit board (PCB), silicon or glass interposer). Specifically, first portion 101 and second portion 102 of the glass-based photonic bridge 110 are disposed under innermost end 124 of the first photonic circuit 120 and innermost end 134 of the second photonic circuit 130, respectively, such that a first surface 116 of the glass-based photonic bridge 110 couples with bottom surfaces of the first photonic circuit 120 and the second photonic circuit 130. The first photonic circuit 120 and the second photonic circuit 130 are placed / positioned in the photonic bridge assembly 100, preferably using chip-on-board technology, and first electrical connection material 140 and second electrical connection material 150 are contacted to the organic substrate 160. In some embodiments, for example, the first electrical connection material 140 and the second electrical connection material 150 may be solder balls, copper pillars, bumps, or any other electrical connection material. In preferred embodiments, the first photonic circuit 120, the second photonic circuit 130, and the glass-based photonic bridge 110 are aligned (e.g., accurate on a Ip scale), and the glass-based photonic bridge 110 connects the first photonic circuit 120 to the second photonic circuit 130 by evanescent coupling.

[0048] The glass-based photonic bridge 110 (e.g., an interposer) has the first surface 116 and a second surface 115. The second surface 115 is opposite the first surface 116. The glass-based photonic bridge 110 includes an optical waveguide 111 within the first surface 116 extending from the first portion 101 of the glass-based photonic bridge 110 to the second portion 102 of the glass-based photonic bridge 110. The first surface 116 is configured to be attachable to the first photonic circuit 120 such that the first portion 101 and the optical waveguide 111 align with the first photonic circuit 120 such that optical signals are able to transfer from the first photonic circuit 120 to the optical waveguide 111. The first surface 116 is further configured to be attachable to the second photonic circuit 130 such that the second portion 102 and the optical waveguide 111 align with the second photonic circuit 130 such that optical signals are able totransfer from the optical waveguide 11 1 to the second photonic circuit 130. The optical waveguide 111 within the first surface 116 serves as an optical connection between the first photonic circuit 120 and the second photonic circuit 130.

[0049] In the embodiment shown in FIG. 1A, the first photonic circuit 120 and the second photonic circuit 130 are adjacent to the substrate 160. Further, the first electrical connection material 140 is positioned between the first photonic circuit 120 and the substrate 160, and the second electrical connection material 150 is positioned between the second photonic circuit 130 and the substrate 160. Notably, in the embodiment shown in FIG. 1 A, the glass-based photonic bridge 110 is also adjacent to the substrate 160. In other embodiments, such as shown and described with respect to FIGs. 2A-3D, the substrate 160 may be electrically connected to second sides of the first photonic circuit 120 and the second photonic circuit 130 that are opposite first sides of the first photonic circuit 120 and the second photonic circuit 130 that are connected to the glass-based photonic bridge 110 such that the glass-based photonic bridge 110 is not adjacent to the substrate 160 (but, rather, is opposite the substrate 160).

[0050] In the embodiment shown in FIG. 1 A, the optical waveguide 111 includes a first portion 122a and a second portion 132a. The first portion 122a and the second portion 132a are shifted upwards such that when the glass-based photonic bridge 110 is packaged, the first portion 122a interacts with a corresponding portion 122b of an optical waveguide in the first photonic circuit 120 and the second portion 132b interacts with a corresponding portion 132b of an optical waveguide in the second photonic circuit 130. It should be appreciated that the optical waveguide 111 may take on any shape. For example, although the optical waveguide 111 in FIG. 1A has the first portion 122a and the second portion 132a that are not linear with the remainder of the optical waveguide 111, in other embodiments, the first portion 122a and the second portion 132a may be such that the entire optical waveguide 111 is configured along a straight line. Other configurations are also contemplated, such as optical waveguides with one or more radii of curvature. In some further embodiments, one or more of the optical waveguide 111, the first photonic circuit 120, and / or the second photonic circuit 130 may have multiple optical waveguides or no optical waveguides.

[0051] It should be appreciated that the optical waveguide 111 can be integrated within the glass-based photonic bridge 110, can be disposed on the glass-based photonic bridge 110, or can be incorporated with the glass-based photonic bridge 110 in any other way. For example, whilea slice of a cross-section of the glass-based photonic bridge 110 is shown, it should be appreciated the example glass-based photonic bridge 110 extends into and out of the page. Along these lines, in some embodiments, different configurations of optical waveguides may be used. Such optical waveguides can extend in any configuration on the first surface 116. Further, in some embodiments, the optical waveguide 111 could be an ion-exchange waveguide, an fs-laser written waveguide, or any other type of waveguide.

[0052] Further, in some embodiments, the glass-based photonic bridge 110 and / or the substrate 160 may be configured such that the glass-based photonic bridge 110 can be embedded in the substrate 160. For example, as shown in FIG. IB, a surface of a substrate 160’ may define an indented portion 103, and a glass-based photonic bridge 110’ (similar to but thicker than the glass-based photonic bridge 110 of FIG. 1A) may be positioned at least partially within the indented portion 103 of the substrate 160’ when the first electrical connection material 140 and the second electrical connection material 150 are positioned for electrical connection between the first photonic circuit 120 and the substrate 160’ and between the second photonic circuit 130 and the substrate 160’, respectively. Additionally, in some embodiments, the photonic bridge assembly 100 may be configured such that a thickness of the glass-based photonic bridge 110’ extending above the substrate 160’ equals a thickness of one or both of the first electrical connection material 140 or the second electrical connection material 150.

[0053] It should be appreciated that, although the glass-based photonic bridge 110 and the glass-based photonic bridge 110' shown in FIGs. 1A-1B each include one optical waveguide, in other embodiments, a glass-based photonic bridge may include more optical waveguides, and the one or more optical waveguides may be configured differently. For example, one or more optical waveguides may be disposed on a second surface (such as the second surface 115) of a glassbased photonic bridge, integrated within an inner portion of a glass-based photonic bridge, or configured any other way.

[0054] In some embodiments, a thickness of the glass-based photonic bridge 110 or the glass-based photonic bridge 110' may be less than 50 microns. Further, in some embodiments, if thicker glass is used (e.g., for handling reasons due to size or material availability), the glass of the glass-based photonic bridge 110 or the glass-based photonic bridge 110' may be thinned by polishing (e.g., CMP (Chemical Mechanical Polishing)) or etching (e.g., HF). The thinness (and other features) of the glass-based photonic bridge 110 or the glass-based photonic bridge 110'may cause the glass-based photonic bridge 110 or the glass-based photonic bridge 1 1 O' to be flexible, which may be advantageous in many embodiments, especially in view of current solutions, which are not flexible. As an example, in some embodiments, a thickness of the glassbased photonic bridge 110 or the glass-based photonic bridge 110' may be between 30 microns and 200 microns and / or between 50 microns and 100 microns. However, other thicknesses are also contemplated within the scope of this disclosure.

[0055] FIGs. 2A-2B schematically illustrate two additional types of photonic bridge assemblies. For example, photonic bridge assembly 200A and photonic bridge assembly 200B may be referred to as flip chip assembly concepts. Photonic bridge assembly 200A shown in FIG. 2A includes glass-based photonic bridge 210a, having an optical waveguide 211a extending from a first portion 201a to a second portion 202a of the glass-based photonic bridge 210a. The optical waveguide 211a includes a first portion 221a configured to interact with a corresponding portion 222a of an optical waveguide in the first photonic circuit 220a and a second portion 233a configured to interact with a corresponding portion 232a of an optical waveguide in the second photonic circuit 230a. Similar to the glass-based photonic bridge 110 discussed above with respect to FIG. 1A, the glass-based photonic bridge 210a of FIG. 2A includes a first surface 216a and a second surface 215a. The first portion 201a and the second portion 202a of the glass-based photonic bridge 210a are disposed onto innermost end 224a of the first photonic circuit 220a and innermost end 234a of the second photonic circuit 230a such that the first surface 216a of the glass-based photonic bridge 210a couples with top surfaces of the first photonic circuit 220a and the second photonic circuit 230a. The first photonic circuit 220a and the second photonic circuit 230a are placed / positioned in the photonic bridge assembly 200 A, preferably using chip-on- board technology, and first electrical connection material 240a and second electrical connection material 250a are contacted to the organic substrate 260a. In some embodiments, for example, the first electrical connection material 240a and the second electrical connection material 250a may be solder balls, copper pillars, bumps, or any other electrical connection material. In preferred embodiments, the first photonic circuit 220a, the second photonic circuit 230a, and the glass-based photonic bridge 210a are aligned (e.g., accurate on a Ip scale), and the glass-based photonic bridge 210a connects the first photonic circuit 220a to the second photonic circuit 230a by evanescent coupling. The glass-based photonic bridge 210a realizes the optical interconnection of the first photonic circuit 220a and the second photonic circuit 230a.

[0056] Photonic bridge assembly 200B shown in FIG. 2B includes a glass-based photonic bridge 210b, having an optical waveguide 211b extending from a first portion 201b to a second portion 202b of the glass-based photonic bridge 210b. The optical waveguide 211a includes a first portion 221b configured to interact with a corresponding portion 222b of an optical waveguide in the first photonic circuit 220b and a second portion 233b configured to interact with a corresponding portion 232b of an optical waveguide in the second photonic circuit 230b. The glass-based photonic bridge 210b of FIG. 2B includes a first surface 216b and a second surface 215b. The first portion 201b and the second portion 202b of the glass-based photonic bridge 210b are disposed onto innermost end 224b of the first photonic circuit 220b and innermost end 234b of the second photonic circuit 230b such that the first surface 216b of the glass-based photonic bridge 210b couples with top surfaces of the first photonic circuit 220b and the second photonic circuit 230b. The first photonic circuit 220b and the second photonic circuit 230b are placed / positioned in the photonic bridge assembly 200B, preferably using chip-on- board technology, and first electrical connection material 240b and second electrical connection material 250b are contacted to the organic substrate 260b. In some embodiments, for example, the first electrical connection material 240b and the second electrical connection material 250b may be solder balls, copper pillars, bumps, or any other electrical connection material. In preferred embodiments, the first photonic circuit 220b, the second photonic circuit 230b, and the glass-based photonic bridge 210b are aligned (e.g., accurate on a Ip scale), and the glass-based photonic bridge 210b connects the first photonic circuit 220b to the second photonic circuit 230b by evanescent coupling. The glass-based photonic bridge 210b realizes the optical interconnection of the first photonic circuit 220b and the second photonic circuit 230b.

[0057] In some embodiments, an attachment of a glass-based photonic bridge to a first photonic circuit and a second photonic circuit may be configured such that the first photonic circuit is substantially and horizontally aligned with the second photonic circuit. For example, as shown in FIG. 2A, the first photonic circuit 220a may be completely and horizontally aligned with the second photonic circuit 230a. Alternatively, as shown in FIG. 2B, the glass-based photonic bridge 210b is flexible and is able to accommodate an unevenness of the first photonic circuit 220b and the second photonic circuit 230b such that the first photonic circuit 220b is substantially and horizontally aligned with the second photonic circuit 230b. In the embodiment shown in FIG. 2B, the unevenness of the first photonic circuit 220b and the second photoniccircuit 230b is caused by a difference in sizing of the first electrical connection material 240b and the second electrical connection material 250b. For example, the first electrical connection material 240b may be solder balls with a diameter that is one tenth of a micrometer, and the second electrical connection material 250b may be solder balls with a diameter that is less than one tenth of a micrometer. Unevenness may be caused over time and / or by inconsistencies in components. The flexibility of the glass-based photonic bridge 210b may be achieved by polishing or etching the glass-based photonic bridge 210b to a desired thickness before or after it is packaged, or the glass-based photonic bridge 210b may be manufactured with flexibility without need for polishing or etching.

[0058] FIGs. 3A-3D illustrate an example process of packaging a glass-based photonic bridge 310. The assembly concept preferably uses a high accuracy placement of a first photonic circuit 320 and a second photonic circuit 330 to the glass-based photonic bridge 310. Electrical interconnects are realized by TSV at backsides of the first photonic circuit 320 and the second photonic circuit 330. After the glass-based photonic bridge 310, the first photonic circuit 320, and the second photonic circuit 330 are sub-assembled, the package is flipped and populated to a substrate 360.

[0059] As shown in FIG. 3A, the process includes providing the glass-based photonic bridge 310, which includes the optical waveguide 311 having a first portion 321 configured to interact with a corresponding portion 322 of an optical waveguide that will be disposed on or in the first photonic circuit 320 and a second portion 333 configured to interact with a corresponding portion 332 of an optical waveguide that will be disposed on or in the second photonic circuit 330. The optical waveguide 311 extends from a first portion 301 of the glass-based photonic bridge 310 to a second portion 302 of the glass-based photonic bridge 310. Further, the glassbased photonic bridge 310 includes a first surface 316 and a second surface 315 opposite the first surface 316.

[0060] As shown in FIG. 3B, the process involves bonding an innermost end 324 of the first photonic circuit 320 to the first surface 316 of the glass-based photonic bridge 310 and bonding an innermost end 334 of the second photonic circuit 330 to the first surface 316 of the glassbased photonic bridge 310. The bonding may be direct bonding, adhesive bonding, or any other type of bonding. Further, the bonding may include disposing the optical waveguide with the corresponding portion 322 onto or into the first photonic circuit 320 and disposing the opticalwaveguide with the corresponding portion 332 onto or into the second photonic circuit 330 such that such optical waveguides are interactable with the first portion 321 and the second portion 333 of the optical waveguide 311. As shown, the first photonic circuit 320 has first electrical connection material 340 disposed on a side of the first photonic circuit 320 that is opposite the glass-based photonic bridge 310, and the second photonic circuit 330 includes second electrical connection material 350 disposed on a side of the second photonic circuit 330 that is opposite the glass-based photonic bridge 310. It should be appreciated that, in other embodiments, the first electrical connection material 340 and the second electrical connection material 350 can be disposed on same sides of the first photonic circuit 320 and the second photonic circuit 330 as the glass-based photonic bridge 310 (e.g., as shown in FIG. 1A). Further, the first electrical connection material 340 and the second electrical connection material 350 can be added at an earlier or later step in other embodiments.

[0061] As shown in FIG. 3C, the glass-based photonic bridge 310 bonded to the first photonic circuit 320 and the second photonic circuit 330 is flipped in a flip chip assembly method. An optical connection between the first photonic circuit 320 and the second photonic circuit 330 is created by placing and / or positioning the glass-based photonic bridge 310 face down (e.g., in a “flip chip” manner) on top of the first photonic circuit 320 and the second photonic circuit 330. When oriented in this manner, light is coupled due to evanescent coupling.

[0062] As shown in FIG. 3D, the assembly may then be connected to the substrate 360 by way of the first electrical connection material 340 and the second electrical connection material 350. Although the first electrical connection material 340 and the second electrical connection material 350 are present beginning in the step shown in FIG. 3 A in this embodiment, in some embodiments, the first electrical connection material 340 and the second electrical connection material 350 may not be added until the step shown in FIG. 3D (or at any other step during the process).

[0063] A thinness of the glass substrate of the glass-based photonic bridge 310 causes a flexibility (e.g., bendability) of the glass-based photonic bridge 310. The thinness can be achieved through initial manufacturing and / or through polishing or etching the glass. The flexibility of the glass-based photonic bridge 310 can compensate for higher tolerances of the first photonic circuit 320 and the second photonic circuit 330 when assembled, as shown particularly in FIG. 2B.

[0064] In the embodiment shown in FIGs. 3A-3D, the first photonic circuit 320 and the second photonic circuit 330 are included individually in the packaging process. However, in other embodiments, the first photonic circuit 320 and the second photonic circuit 330 may be included in a wafer or a chip. For example, in some embodiments, a wafer may include a first die and a second die, or any other configuration. Further, the wafer and / or the components thereon may include additional optical waveguides that may or may not be configured to communicate with the optical waveguide 311 of the glass-based photonic bridge 310. Further, in some embodiments, the wafer can be replaced by a heterogeneous target wafer after a transfer printing process. The wafer may be a system-in-package (SiP) wafer or any other type of wafer.

[0065] The optical interface can be, for example, evanescent, or edge coupled. With this approach, different photonic circuits can be attached to the glass-based photonic bridge 310, and the assembly can include photonic interconnections as well as electrical interconnections for signal processing, memory, sensing or other applications and needs.

[0066] FIGs. 4A-4B show a first packaging flow concept 420 and a second packaging flow concept 438. As shown in FIG. 4A, the first packaging flow concept 420 begins by providing a PIC wafer at 422. For example, the PIC wafer may include a first photonic circuit and a second photonic circuit, as described herein. Other configurations are also contemplated within the scope of this disclosure. A glass-based photonic bridge 426 is then bonded at 428 using a wafer bonding process. At 430, solder balls are attached. At 432, a reflow process is executed. For example, the reflow process at 432 may include applying solder paste to contact pads of a PCB, placing components on, and then melting the solder paste with heated air to join the electrical components. The solder “reflows” to make the connection. At 434, a dicing process may be executed. For example, the dicing process at 434 may include separating photonic circuits from the PIC wafer following the processing of the PIC wafer. The dicing process may involve scribing and breaking, mechanical sawing, laser cutting, and / or any other separation method. After dicing, the resulting multiple die modules (along with the glass-based photonic bridge) can be attached to the final substrate using a standard flip chip process at 436. The first packaging flow concept 420 enables a best selection regarding performance and cost for the glass-based photonic bridge (e.g., glass with low-loss waveguides) and non-optical electrical material, such as organic printed circuit boards (PCBs) or others dependent on application.

[0067] As shown in FIG. 4B, the second packaging flow concept 438 may use a glass-based photonic bridge 440 as a target wafer. Transfer printing is executed at 444, and then the assembled package follows a similar process flow like the first packaging flow concept 420. For example, at 446, solder balls are attached. At 448, a reflow process is executed. For example, the reflow process at 448 may include applying solder paste to contact pads of a PCB, placing components on, and then melting the solder paste with heated air to join the electrical components. The solder “reflows” to make the connection. At 450, a dicing process may be executed. For example, the dicing process at 450 may include separating the photonic integrated circuits. The dicing process may involve scribing and breaking, mechanical sawing, laser cutting, or any other separation method. After dicing, the resulting multiple die modules can be attached to the final substrate using a standard flip chip process at 452.

[0068] It should be appreciated that the packaging concepts shown and described with respect to FIGs. 4A-4B are only two examples, and that other packaging concepts are also contemplated within the scope of this disclosure. For example, although a first photonic circuit and a second photonic circuit may be disposed on a PIC wafer or a PIC chip, in some embodiments, a first photonic circuit and a second photonic circuit may be used without a PIC wafer or PIC chip. Further, the packaging process may be configured differently than that shown in FIGs. 4A-4B.Example Flowchart! s)

[0069] FIG. 5 illustrates a flowchart according to an example method 500 of packaging a glass-based photonic bridge according to an example embodiment. The method 500 may include providing the glass-based photonic bridge at operation 502. The glass-based photonic bridge provided at operation 502 may include a first surface, a second surface opposite the first surface, and an optical waveguide within the first surface extending from a first portion of the glass-based photonic bridge to a second portion of the glass-based photonic bridge.

[0070] At operation 504, the method 500 may include attaching the first surface to a first photonic circuit such that the first portion and the optical waveguide align with the first photonic circuit such that optical signals are able to transfer from the first photonic circuit to the optical waveguide. Additionally, at operation 506, the method 500 may include attaching the first surface to a second photonic circuit such that the second portion and the optical waveguide alignwith the second photonic circuit such that optical signals are able to transfer from the optical waveguide to the second photonic circuit.

[0071] At operation 508, in some embodiments, the method 500 may include positioning the first photonic circuit and the second photonic circuit adjacent to a substrate. In some embodiments, for example, operation 508 may include flipping the subassembly of the glassbased photonic bridge, first photonic circuit, and second photonic circuit, as shown and described with respect to FIGs. 3A-3D. Alternatively, the positioning may be done such that the glassbased photonic bridge is adjacent to the substrate or such that the glass-based photonic bridge is opposite the substrate such that the substrate may be electrically connected to second sides of the first photonic circuit and the second photonic circuit that are opposite first sides of the first photonic circuit and the second photonic circuit that are connected to the glass-based photonic bridge, as described herein. Operation 508 may be optional.

[0072] At operation 510, in some embodiments, the method 500 may include positioning an electrical connection material between the first photonic circuit and the substrate and between the second photonic circuit and the substrate. In some embodiments, for example, the electrical connection material may be one or more solder balls, bumps, and / or copper pillars. Operation 510 may be optional and / or performed prior to or in conjunction with any of the other operations described herein.

[0073] Additional manufacturing operations and / or additional usage operations are also contemplated. For example, in some embodiments, the method 500 may further include thinning the glass-based photonic bridge by polishing or etching. However, in other embodiments, the glass-based photonic bridge may already have a desired thickness and may not require polishing or etching. Further, in some embodiments, the method 500 may further include attaching fiber connector receptacles at edges of the glass-based photonic bridge. Other operations are also contemplated within the scope of this disclosure. Such operations may be optional.

[0074] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.Conclusion

[0075] Many modifications and other embodiments of the disclosures set forth herein may come to mind to one skilled in the art to which these disclosures pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the embodiments of the disclosure are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the disclosure. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and / or functions, it should be appreciated that different combinations of elements and / or functions may be provided by alternative embodiments without departing from the scope of the disclosure. In this regard, for example, different combinations of elements and / or functions than those explicitly described above are also contemplated within the scope of the disclosure. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

WHAT IS CLAIMED:

1. A glass-based photonic bridge comprising: a first surface; a second surface opposite the first surface; and an optical waveguide within the first surface extending from a first portion of the glassbased photonic bridge to a second portion of the glass-based photonic bridge, wherein the first surface is configured to be attachable to a first photonic circuit such that the first portion and the optical waveguide align with the first photonic circuit such that optical signals are able to transfer from the first photonic circuit to the optical waveguide, wherein the first surface is further configured to be attachable to a second photonic circuit such that the second portion and the optical waveguide align with the second photonic circuit such that optical signals are able to transfer from the optical waveguide to the second photonic circuit, wherein the optical waveguide within the first surface serves as an optical connection between the first photonic circuit and the second photonic circuit.

2. The glass-based photonic bridge of claim 1, wherein the first photonic circuit and the second photonic circuit are adjacent to a substrate, and wherein an electrical connection material is positioned between the first photonic circuit and the substrate and between the second photonic circuit and the substrate.

3. The glass-based photonic bridge of claim 2, wherein the glass-based photonic bridge is adjacent to the substrate.

4. The glass-based photonic bridge of claim 3, wherein a surface of the substrate defines an indented portion, and wherein the glass-based photonic bridge is positioned at least partially within the indented portion when the electrical connection material is positioned for electrical connection between the first photonic circuit and the substrate and between the second photonic circuit and the substrate.

5. The glass-based photonic bridge of any one of claims 2-4, wherein a first thickness of the glass-based photonic bridge extending above the substrate equals a second thickness of the electrical connection material.

6. The glass-based photonic bridge of claim 2, wherein the substrate is electrically connected to second sides of the first photonic circuit and the second photonic circuit that are opposite first sides of the first photonic circuit and the second photonic circuit that are connected to the glass-based photonic bridge.

7. The glass-based photonic bridge of any one of claims 2-6, wherein the electrical connection material includes solder balls.

8. The glass-based photonic bridge of claim 7, wherein the solder balls have a diameter that is one tenth of a micrometer.

9. The glass-based photonic bridge of any one of claims 2-6, wherein the electrical connection material includes one or more bumps or copper pillars.

10. The glass-based photonic bridge of any one of claims 1-9, wherein the glass-based photonic bridge is embedded in a substrate.

11. The glass-based photonic bridge of any one of claims 1-10, wherein a thickness of the glass-based photonic bridge is between 30 microns and 200 microns.

12. The glass-based photonic bridge of any one of claims 1-9, wherein a thickness of the glass-based photonic bridge is between 50 microns and 100 microns.

13. The glass-based photonic bridge of any one of claims 1-9, wherein a thickness of the glass-based photonic bridge is 50 microns.

14. The glass-based photonic bridge of any one of claims 1-13, wherein the glass-based photonic bridge is polished to a desired thickness at least one of during or after a packaging process.

15. The glass-based photonic bridge of any one of claims 1-14, wherein the glass-based photonic bridge is substantially flexible.

16. The glass-based photonic bridge of any one of claims 1-15, wherein the glass-based photonic bridge comprises at least two optical waveguides.

17. The glass-based photonic bridge of any one of claims 1-16, wherein the first photonic circuit comprises at least one first optical waveguide, and wherein the second photonic circuit comprises at least one second optical waveguide.

18. The glass-based photonic bridge of any one of claims 1-17, wherein an attachment of the glass-based photonic bridge to the first photonic circuit and the second photonic circuit is configured such that the first photonic circuit is substantially and horizontally aligned with the second photonic circuit.

19. The glass-based photonic bridge of any one of claims 1-17, wherein an attachment of the glass-based photonic bridge to the first photonic circuit and the second photonic circuit is configured such that the first photonic circuit is not horizontally aligned with the second photonic circuit.

20. A method of packaging a glass-based photonic bridge, the method comprising: providing the glass-based photonic bridge, the glass-based photonic bridge comprising: a first surface; a second surface opposite the first surface; and an optical waveguide within the first surface extending from a first portion of the glass-based photonic bridge to a second portion of the glass-based photonic bridge;attaching the first surface to a first photonic circuit such that the first portion and the optical waveguide align with the first photonic circuit such that optical signals are able to transfer from the first photonic circuit to the optical waveguide; and attaching the first surface to a second photonic circuit such that the second portion and the optical waveguide align with the second photonic circuit such that optical signals are able to transfer from the optical waveguide to the second photonic circuit, wherein the optical waveguide within the first surface serves as an optical connection between the first photonic circuit and the second photonic circuit.

21. The method of claim 20, wherein the method further comprises: positioning the first photonic circuit and the second photonic circuit adjacent to a substrate; and positioning an electrical connection material between the first photonic circuit and the substrate and between the second photonic circuit and the substrate.

22. The method of claim 21, wherein the glass-based photonic bridge is adjacent to the substrate.

23. The method of claim 21, wherein the substrate is electrically connected to second sides of the first photonic circuit and the second photonic circuit that are opposite first sides of the first photonic circuit and the second photonic circuit that are connected to the glass-based photonic bridge.

24. The method of any one of claims 20-23, wherein the method further comprises thinning the glass-based photonic bridge by polishing or etching.

25. The method of any one of claims 20-24, wherein the method further comprises attaching fiber connector receptacles at edges of the glass-based photonic bridge.

26. A glass-based photonic bridge assembly comprising: a glass-based photonic bridge comprising:a first surface; a second surface opposite the first surface; and an optical waveguide within the first surface extending from a first portion of the glass-based photonic bridge to a second portion of the glass-based photonic bridge; a first photonic circuit attached to the first surface of the glass-based photonic bridge such that the first portion and the optical waveguide align with the first photonic circuit such that optical signals are able to transfer from the first photonic circuit to the optical waveguide; a second photonic circuit attached to the first surface of the glass-based photonic bridge such that the second portion and the optical waveguide align with the second photonic circuit such that optical signals are able to transfer from the optical waveguide to the second photonic circuit; and a substrate connected to the first photonic circuit and the second photonic circuit by way of an electrical connection material disposed between the substrate and each of the first photonic circuit and the second photonic circuit, wherein the optical waveguide within the first surface serves as an optical connection between the first photonic circuit and the second photonic circuit.

27. The glass-based photonic bridge assembly of claim 26, wherein the glass-based photonic bridge is adjacent to the substrate.

28. The glass-based photonic bridge assembly of claim 26, wherein the glass-based photonic bridge is opposite the substrate relative to the first photonic circuit and the second photonic circuit.

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