Integrated glass waveguide component for polarization control, and corresponding- systems, assemblies, and methods

Abstract

An integrated glass waveguide assembly is provided. The integrated glass waveguide assembly includes a core unit assembly, and the core unit assembly includes a substrate, a transceiver chip attached to the substrate, and a polarization maintaining optical waveguide comprising a first end and a second end. The first end is connected to the transceiver chip, the second end is positioned proximate to an edge of the substrate, and the second end is configured to be connected to a polarization maintaining fiber to form an optical path with a laser module.

Description

INTEGRATED GLASS WAVEGUIDE COMPONENT FOR POLARIZATION CONTROL, AND CORRESPONDING SYSTEMS, ASSEMBLIES, AND METHODS PRIORITY APPLICATIONS

[0001] This application claims the benefit of priority U.S. Provisional Application Serial No. 63 / 668,575 filed on July 8, 2024, the content of which is relied upon and incorporated herein by reference in its entirety. FIELD

[0002] Embodiments relate generally to integrated glass waveguide assemblies including polarization maintaining optical waveguides that, for example, connect directly to a laser module. BACKGROUND

[0003] For co-packaged optic applications, light sources may be positioned on the same chip as an optical modulator. However, with this approach, the light sources may possess limited reliability as the light sources may be exposed to high temperatures over its lifetime. This approach also leads to limited serviceability for the light sources, with the light sources potentially being difficult to exchange when they fail. This approach also limits the number of light sources that may be used, as the light sources must be compatible with other components on the chip. BRIEF SUMMARY

[0004] Laser modules such as External Laser Small Form Factor Pluggable (ELSFP) modules are sometimes used in co-packaged optic applications, with these ELSFP modules being external laser sources that are not positioned on the same chip as an optical modulator.

[0005] In various embodiments described herein, integrated glass waveguide assemblies may be provided having a glass circuit board with optical waveguides embedded in the glass circuit board and directly connected to a laser module. The optical waveguides may include a polarization maintaining optical waveguide that may serve as a continuous wave laser source. The polarization maintaining optical waveguide may be configured to maintain polarization to couple light from a laser module to another component for polarization dependent modulation. The polarization maintaining optical waveguide may be formed through an ion-exchange process, and the optical waveguides may be optimized to support large coupling tolerances and to handle high optical power. Integrated glass waveguide assemblies may also include a component that may contain apolarization sensitive modulator, and the polarization maintaining optical waveguide may form an optical connection to a transceiver chip and other components attached to the transceiver chip (e.g., application specific integrated circuits, switch chips, etc.). Integrated glass waveguide assemblies of various embodiments described herein may be made in a cost-effective manner and with a high assembly throughput.

[0006] In some embodiments, integrated glass waveguide assemblies may be made without any electrical printed circuit board, and integrated glass waveguide assemblies may be made without polarization maintaining optical fibers being used to connect a module to a transceiver chip or other components on the integrated glass waveguide assemblies. Instead, a glass circuit board may be used, and polarization maintaining optical waveguides may connect to the laser module at one end and may connect to a transceiver chip or another component on the integrated glass waveguide assemblies at another end. However, in other embodiments, integrated glass waveguide assemblies may include an electrical printed circuit board and polarization maintaining optical fibers.

[0007] Embodiments described herein may enable high temperature stability of optical waveguides such as polarization maintaining optical waveguides where the optical power is about 100 milliwatts or more, about 250 milliwatts or more, about 500 milliwatts or more, etc. Embodiments described herein may also enable small temperature dependency of glass, with a negligible impact on the refractive index as the temperature is changed.

[0008] Optical waveguide pitches proximate to a core unit assembly or transceiver chips within the core unit assembly may be less than about 50 micrometers, thereby allowing a high interconnect density to be accomplished. Polarization maintaining optical waveguides may support highly efficient and low loss evanescent coupling to components such as laser components. Polarization maintaining optical waveguides may also support low loss end-face, grating, evanescent, or free-space coupling to laser modules or to fibers such as optical fibers. Polarization maintaining optical waveguides may possess an efficiency of about 80 percent or more. Embodiments may utilize optical waveguides that effectively control the beat length, thereby allowing a polarization extinction ratio and other properties for the optical waveguides to beoptimized. The beat length is the length required for a 2 phase shift to build up between the fastand slow axes of the optical waveguide.

[0009] Additionally, optical waveguides may be provided in the form of an optical splitter, with a first segment of the optical waveguides splitting into multiple segments. Where this is the case, the first segment may be connected to a laser module to obtain external laser power, and the additional split segments may be connected to a transceiver chip or another component. The transceiver chip may have optical waveguides included therein having significantly smaller waveguide dimensions and higher confined optical modes. The power density for the optical waveguides in the transceiver chip may be high for these smaller optical waveguides relative to other optical waveguides outside of the transceiver chip, and this may lead to damage for the transceiver optical waveguides. Where an optical waveguide dimension (width or height) for transceiver optical waveguides is less than about 1 micrometer, the use of an optical splitter may reduce power transmission for evanescent or edge coupling to a transceiver chip or to another component, and this may enable a reduction in power density at the transceiver optical waveguides. The use of optical waveguides in the form of an optical splitter may also enable integration of fan- in or fan-out layouts in an optical circuit.

[0010] In some embodiments, assemblies may be used in products with electrical packaging and in optical circuit board products. Assemblies may provide high-density fiber-to-chip connectors, and assemblies may also provide co-packaging of optics and effective control of polarization for polarization maintaining optical waveguides.

[0011] In an example embodiment, an integrated glass waveguide assembly is provided. The integrated glass waveguide assembly includes a core unit assembly comprising a substrate. The integrated glass waveguide assembly also includes a transceiver chip attached to the substrate. The integrated glass waveguide assembly also includes a polarization maintaining optical waveguide comprising a first end and a second end. The first end is connected to the transceiver chip, the second end is positioned proximate to an edge of the substrate, and the second end is configured to be connected to a polarization maintaining fiber to form an optical path with a laser module.

[0012] In some embodiments, the polarization maintaining fiber may be included as part of the integrated glass waveguide assembly. Additionally, in some embodiments, the laser module may be included as part of the integrated glass waveguide assembly. Furthermore, in some embodiments, the integrated glass waveguide assembly may also include an electrical printed circuit board, and the laser module may be attached to the electrical printed circuit board.

[0013] In some embodiments, the substrate may comprise glass, and the polarization maintaining optical waveguide may be fabricated into the substrate. In some embodiments, the core unit assembly may also include a waveguide interconnect comprising glass, the waveguide interconnect is attached to the substrate, and wherein the polarization maintaining optical waveguide is fabricated into the waveguide interconnect.

[0014] In some embodiments, the integrated glass waveguide assembly may also include a glass-waveguide-to-fiber connector. The second end of the polarization maintaining optical waveguide may be directly connected to the glass-waveguide-to-fiber connector, and the glass- waveguide-to-fiber connector may be directly connected to the polarization maintaining fiber.

[0015] In some embodiments, the integrated glass waveguide assembly may also include a non-polarization maintaining fiber. The core unit assembly may also include a non-polarization maintaining optical waveguide. One end of the non-polarization maintaining optical waveguide may be connected to the transceiver chip. Another end of the non-polarization maintaining optical waveguide may be positioned proximate to the edge of the substrate and may be connected to the non-polarization maintaining fiber to form a second optical path with another component. Additionally, in some embodiments, the substrate may comprise glass, and the non-polarization maintaining optical waveguide may be fabricated into the substrate. In some embodiments, the core unit assembly may also include a waveguide interconnect comprising glass, the waveguide interconnect may be attached directly or indirectly to the substrate, and the non-polarization maintaining optical waveguide may be fabricated into the waveguide interconnect.

[0016] In some embodiments, the core unit assembly may also include a first component and an electrical interconnect. The first component may comprise an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, and / or a memory chip. The electrical interconnect may connect the transceiver chip to the first component.

[0017] In another example embodiments, an integrated glass waveguide assembly is provided. The integrated glass waveguide assembly includes a glass circuit board, a core unit assembly, at least one polarization maintaining optical waveguide, and a non-polarization maintaining optical waveguide. The core unit assembly comprises a transceiver chip, and the core unit assembly is attached to the glass circuit board. The non-polarization maintaining optical waveguide is configured to connect to the core unit assembly. Each polarization maintaining optical waveguide of the polarization maintaining optical waveguide(s) comprises a first end and a second end. Thefirst end(s) are connected to the core unit assembly, and the second end(s) are configured to be connected to the laser module. The polarization maintaining optical waveguide(s) and the non- polarization maintaining optical waveguide are each fabricated into the glass circuit board.

[0018] In some embodiments, the core unit assembly may also include a first component and an electrical interconnect. The first component may include an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, and / or a memory chip. The electrical interconnect may connect the transceiver chip to the first component.

[0019] In some embodiments, the integrated glass waveguide assembly may also include a glass-waveguide-to-fiber connector. A first end of the non-polarization maintaining optical waveguide may be connected to the transceiver chip, and a second end of the non-polarization maintaining optical waveguide may be connected to the glass-waveguide-to-fiber connector.

[0020] In some embodiments, the integrated glass waveguide assembly may not include any polarization maintaining optical fibers. In some embodiments, the integrated glass waveguide assembly may not include an electrical printed circuit board. In some embodiments, the integrated glass waveguide assembly may not include multiple glass waveguide interconnects. In some embodiments, the integrated glass waveguide assembly may also include a laser module. Furthermore, in some embodiments, the non-polarization maintaining optical waveguide or the polarization maintaining optical waveguide(s) may comprise potassium and / or silver. In some embodiments, a first polarization maintaining optical waveguide of the polarization maintaining optical waveguide(s) may include a first segment and additional segments, the first segment may be connected to the laser module, the first segment may split into the additional segments, and each of the additional segments may be connected to the core unit assembly. In some embodiments, each polarization maintaining optical waveguide of the polarization maintaining optical waveguide(s) may have a propagation length of between about 3 millimeters and about 500 millimeters. In some embodiments, the polarization maintaining optical waveguide(s) may comprise a high birefringence section and a low birefringence section, and the high birefringence section may have a higher birefringence relative to the low birefringence section.

[0021] In some embodiments, each polarization maintaining optical waveguide of the polarization maintaining optical waveguide(s) may have a polarization extinction ratio of about 23 decibels or more when an angular misalignment is less than about three degrees. Additionally, in some embodiments, each polarization maintaining optical waveguide of the polarizationmaintaining optical waveguide(s) may define a propagation length and a beat length. A length ratio value may be the propagation length divided by the beat length, and the ratio value may be less than about 0.02 away from half of an integer.

[0022] In another example embodiment, a method for making an integrated glass waveguide assembly is provided. The method comprises fabricating a polarization maintaining optical waveguide in a glass circuit board, and the polarization maintaining optical waveguide comprises a first end and a second end. The method also comprises fabricating a non-polarization maintaining optical waveguide in the glass circuit board, and the non-polarization maintaining optical waveguide comprises a first end and a second end. The method also comprises attaching a core unit assembly to the glass circuit board. The core unit assembly comprises a transceiver chip. The method also comprises connecting the core unit assembly to the first end of the polarization maintaining optical waveguide and to the first end of the non-polarization maintaining optical waveguide, attaching a laser module to the second end of the polarization maintaining optical waveguide, and attaching a glass-waveguide-to-fiber connector to the second end of the non- polarization maintaining optical waveguide.

[0023] In some embodiments, the transceiver chip of the core unit assembly may be connected to the first end of the polarization maintaining optical waveguide and to the first end of the non- polarization maintaining optical waveguide. The core unit assembly may comprise a first component and an electrical interconnect. The first component may comprise an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, and / or a memory chip, and the electrical interconnect may connect the transceiver chip and the first component.

[0024] In some embodiments, fabricating the polarization maintaining optical waveguide in the glass circuit board may include completing an ion-exchange cycle with a first material, and the first material may include at least one of silver or potassium. Additionally, in some embodiments, the ion-exchange cycle may be performed at a first temperature, fabricating the non-polarization maintaining optical waveguide in the glass core or glass circuit board may include completing a second ion-exchange cycle with a second material at a second temperature, the second ion- exchange cycle may be completed after the first ion-exchange cycle, the first temperature may be higher than the second temperature, and the first material may be different than the second material. In some embodiments, the first material may include potassium, and the second materialmay include silver. Additionally, in some embodiments, the method may also include positioning mask(s) on a surface of the glass circuit board. The mask(s) may leave an exposed surface area on the glass circuit board, the mask(s) are positioned before completing any ion-exchange cycle. Furthermore, in some embodiments, the method may also include removing the mask(s) from the surface of the glass circuit board and completing an additional ion-exchange cycle using a material comprising sodium after the mask(s) have been removed from the surface of the glass circuit board.

[0025] In some embodiments, the glass circuit board that is formed may not include any polarization maintaining optical fibers, the glass circuit board may not include any electrical printed circuit board, and the glass circuit board may not include multiple glass waveguide interconnects. In some embodiments, the polarization maintaining optical waveguide may have a polarization extinction ratio of about 23 decibels or more with an angular misalignment of less than about three degrees, the polarization maintaining optical waveguide may define a length and a beat length, a ratio value may be the length divided by the beat length, and the ratio value may be less than about 0.02 away from half of an integer.

[0026] In another example embodiment, an integrated glass waveguide system is provided. The integrated glass waveguide system includes a laser module and an integrated glass waveguide assembly. The integrated glass waveguide assembly includes a glass circuit board, a core unit assembly comprising a transceiver chip, polarization maintaining optical waveguide(s), and a non- polarization maintaining optical waveguide. Each polarization maintaining optical waveguide of the polarization maintaining optical waveguide(s) comprises a first end and a second end. The non- polarization maintaining optical waveguide is configured to connect to the core unit assembly. The first end of each polarization maintaining optical waveguide is connected to the core unit assembly, and the second end of each polarization maintaining optical waveguide is configured to be connected to the laser module. The core unit assembly is attached to the glass circuit board, and the polarization maintaining optical waveguide(s) and the non-polarization maintaining optical waveguide are each fabricated into the glass circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0028] FIGS.1A–1B are top, schematic views illustrating different assemblies for connecting laser modules to transceiver chips, in accordance with some embodiments discussed herein;

[0029] FIG.1C is a side, schematic view illustrating a laser module, in accordance with some embodiments discussed herein;

[0030] FIG.2A is a top, schematic view illustrating an assembly for connecting a laser module to a transceiver chip, with the assembly including polarization maintaining optical fibers, in accordance with some embodiments discussed herein;

[0031] FIG.2B is a top, schematic view illustrating another example assembly for connecting a laser module to a transceiver chip, with the assembly including polarization maintaining optical fibers, in accordance with some embodiments discussed herein;

[0032] FIG. 3 is a top, schematic view illustrating an example assembly comprising a glass circuit board, with the assembly being configured to connect a laser module such as an ELSFP module to a transceiver chip of a core unit assembly without requiring polarization maintaining optical fibers, in accordance with some embodiments discussed herein;

[0033] FIGS. 4A–4C are top, schematic views illustrating example assemblies similar to the assembly of FIG. 3, where laser modules are positioned in various locations relative to the glass circuit boards, in accordance with some embodiments discussed herein;

[0034] FIG. 5 is a top, schematic view illustrating an example assembly that includes a polarization maintaining optical waveguide comprising a segment that is split into four separate segments, with each of the segments being connected to the core unit assembly, in accordance with some embodiments discussed herein;

[0035] FIG. 6 is a flow chart illustrating an example method for forming polarization maintaining optical waveguides within a glass circuit board, in accordance with some embodiments discussed herein;

[0036] FIG. 7 is a schematic view illustrating the various operations of the method of FIG. 6 being performed, in accordance with some embodiments discussed herein;

[0037] FIG. 8 is a flow chart illustrating an example method for forming optical waveguides within a glass circuit board, in accordance with some embodiments discussed herein;

[0038] FIGS.9A–9D are schematic views illustrating the various operations of the method of FIG. 8 being performed to create different assemblies, in accordance with some embodiments discussed herein;

[0039] FIG.10 is a side, schematic view illustrating an assembly with polarization maintaining optical waveguides comprising silver formed within a glass circuit board, in accordance with some embodiments discussed herein;

[0040] FIG. 11 is a plot illustrating an example refractive index profile for a portion of the glass circuit board of FIG. 10 proximate to a polarization maintaining optical waveguide, in accordance with some embodiments discussed herein;

[0041] FIG.12 is a side, schematic view illustrating an assembly with polarization maintaining optical waveguides comprising potassium formed within a glass circuit board, in accordance with some embodiments discussed herein;

[0042] FIG.13 is a side, schematic view illustrating an assembly with polarization maintaining optical waveguides comprising silver formed within another glass circuit board comprising a different type of glass relative to the glass circuit boards of FIGS. 10 and 12, in accordance with some embodiments discussed herein;

[0043] FIG. 14 is a plot illustrating power output for a polarization maintaining optical waveguide over the course of 37 days, in accordance with some embodiments discussed herein;

[0044] FIG. 15 is a schematic view illustrating an example testing assembly for obtaining the test results illustrated in FIG.16, in accordance with some embodiments discussed herein;

[0045] FIG.16 is a line graph illustrating the polarization extinction ratio as a function of input polarization angle for polarization maintaining optical waveguides having different propagation lengths, in accordance with some embodiments discussed herein;

[0046] FIG. 17 is a line graph illustrating the polarization extinction ratio as a function of angular misalignment for polarization maintaining optical waveguides having different propagation lengths, in accordance with some embodiments discussed herein;

[0047] FIGS. 18A–18B are a side, schematic view illustrating assemblies with polarization maintaining optical waveguides formed within a glass circuit board with high and low birefrigence sections, in accordance with some embodiments discussed herein;

[0048] FIG. 18C is a top, schematic view illustrating an assembly having polarization maintaining optical waveguides formed within a glass circuit board with high and low birifrigence sections, in accordance with some embodiments discussed herein;

[0049] FIG. 19A is a line graph illustrating the polarization extinction ratio when different waveguide lengths are used, with the waveguide lengths stated in terms of the waveguide length divided by the beat length, in accordance with some embodiments discussed herein;

[0050] FIG.19B is an enhanced view of the line graph of FIG.19A that focuses on waveguide lengths ranging between 0.95 times the beat length and 1.00 times the beat length, in accordance with some embodiments discussed herein;

[0051] FIG. 20 is a flow chart illustrating an example method for making an integrated glass waveguide assembly, in accordance with some embodiments discussed herein;

[0052] FIG. 21 is a flow chart illustrating an example method for making an integrated glass waveguide assembly, in accordance with some embodiments discussed herein; and

[0053] FIG. 22 is a flow chart illustrating an example method for making an integrated glass waveguide assembly, in accordance with some embodiments discussed herein. DETAILED DESCRIPTION

[0054] Example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments are shown. Like reference numerals generally refer to like elements throughout. For example, reference numbers 114, 214, 214A, 314, 414A, 414B, and 414C each refer to laser modules. Additionally, any connections or attachments may be direct or indirect connections or attachments unless specifically noted otherwise.

[0055] FIG. 1A is a top, schematic view illustrating an assembly 100A for connecting a laser module 114 to a transceiver chip. The laser module 114 is an ELSFP module that is a faceplate pluggable form factor configured to address the laser packaging requirements for co-packaged optical (CPO) systems with optical engines (OE) which do not have integrated lasers but instead choose to locate lasers external to the optical engines. The assembly 100A also includes an electrical printed circuit board 102, a co-packaged optic substrate 104A, a component 106A, co- packaged optic modules 108, non-polarization maintaining optical fibers 110, polarization maintaining optical fibers 112, connectors 116. The component 106A may be a switch chip or an application-specific integrated circuit (ASIC). The co-packaged optic modules 108 comprise optical engines such as photonic integrated chips (e.g., silicon photonic integrated chips) positioned thereon, and the co-packaged optic modules 108 serve as the interface where polarization maintaining optical fibers are connected to form an optical link with components onthe co-packaged optic substrate 104A. A connector interface is needed on the optical engines of the co-packaged optic modules 108 for solder compatibility to enable a higher level of integration (e.g., heterogeneous integration) and power efficient systems.

[0056] Where the laser module 114 is used that is not integrated on the co-packaged optic substrate 104A, a polarization maintaining optical fiber 112 may connect the laser module 114 with components on the co-packaged optic substrate 104A such as the co-packaged optic modules 108 and the component 106A. These polarization maintaining optical fibers 112 are more expensive than non-polarization maintaining optical fibers 110, and this is especially the case because polarization maintaining optical fibers 112 must be angularly aligned with connection interfaces with at least an angular precision of ± 3 degrees to accomplish effective coupling of these fibers.

[0057] Decoupling the laser module 114 from the co-packaged optic substrate 104A may increase serviceability for the laser module 114 as the laser module 114 may be exchanged when it fails. Decoupling the laser module 114 from the co-packaged optic substrate 104A may increase compatibility as a greater number of vendors may be capable of providing a laser module external to the co-packaged optic substrate 104A. Decoupling the laser module 114 from the co-packaged optic substrate 104A may increase reliability for the laser module 114 as the laser module 114 may be exposed to lower temperatures over its lifetime.

[0058] The laser module 114 and other laser modules described herein may meet the requirements of the External Laser Small Form Factor Pluggable (ELSFP) Implementation Agreement (OIF-ELSFP-01.0) provided by OIF and dated August 8, 2023, and these requirements are incorporated herein by reference for all purposes.

[0059] The assembly 100A also includes an external circuit board assembly 120, and connections 118 may extend between connectors 116 positioned on the electrical printed circuit board 102 and connectors 122 positioned on the external circuit board assembly 120. These connections 118 may be non-polarization maintaining optical fibers. Other connectors 116 are positioned on the external circuit board assembly 120 and may be used to facilitate connections to other components external to the electrical printed circuit board 102. The connectors 116 may each be fiber-to-fiber connectors, but other connectors may be used as well. Each of the non-polarization maintaining optical fibers 110 extending from the connectors 116 to the co-packaged optic modules 108 may be non-polarization maintaining optical fibers.

[0060] FIG. 1B is a top, schematic view illustrating another assembly 100B for connecting a laser module 114 to an assembly on co-packaged optic substrate 104B. The assembly 100B is similar to the assembly 100A in most respects, but the assembly 100B includes a different assembly at the co-packaged optic substrate 104B. Co-packaged optic modules 108A, 108B are positioned on the co-packaged optic substrate 104B, and the co-packaged optic modules 108A, 108B are similar to the co-packaged optic modules 108 of FIG. 1A. Polarization maintaining optical fibers 112 are connected to the co-packaged optic modules 108A and non-polarization maintaining optical fibers 110A are connected to the co-packaged optic module 108B, and these connections form an optical link between components on the co-packaged optic substrate 104B and components external to the co-packaged optic substrate 104B.

[0061] Components on the co-packaged optic substrate 104B include a memory chip 128, which may be connected to external memory. Components on the co-packaged optic substrate 104B also include a communications chip 130 that may be connected to other components (e.g., through an ethernet connection). A component 106B is also positioned on the co-packaged optic substrate 104B, with the component 106B being a switch chip. However, the component 106B may be something other than a switch chip in other embodiments. Other components may also be positioned on the co-packaged optic substrate 104B.

[0062] A side, schematic view illustrating a laser module 114 in the form of an ELSFP module is illustrated in FIG.1C. The laser module 114 may include a printed circuit board 136, an optical connector 134 positioned on the printed circuit board 136, a DC-DC converter 138, a packaged laser 142, a microcontroller 191, and a connection line 144. The connection line 144 may extend from the optical connector 134 to conductive material below the printed circuit board 136. The optical connector 134 may also be connected to the packaged laser 142 via a connection line 193.

[0063] FIG. 2A is a top, schematic view illustrating an assembly 246 for connecting a laser module 214 to a transceiver chip 256, with the assembly 246 using polarization maintaining optical fibers 268 to form an optical link connecting the laser module 214 to the transceiver chip 256. The assembly 246 includes an electrical printed circuit board 202, which may comprise organic material. The assembly 246 also includes a faceplate 258 attached to a side of the electrical printed circuit board 202. The assembly 246 also includes a core unit assembly 245. The core unit assembly 245 includes a co-packaged optic substrate 248 positioned at an internal location on the electrical printed circuit board 202 such that the co-packaged optic substrate 248 is surrounded bythe electrical printed circuit board 202. The core unit assembly 245 also includes the transceiver chip 256, which is attached to the co-packaged optic substrate 248. The core unit assembly 245 also includes polarization maintaining optical waveguides 264, electrical interconnects 260, non- polarization maintaining optical waveguides 262, transceiver chips 256, and glass waveguide interconnects 252.

[0064] A component 250 is also included in the core unit assembly 245, with the component 250 positioned on the co-packaged optic substrate 248. The component 250 may be an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, or a memory chip. Additionally, the transceiver chips 256 are positioned on the co-packaged optic substrate 248, and the transceiver chips 256 are attached to the component 250 using electrical interconnects 260. The transceiver chips 256 and other transceiver chips described herein may be configured to enable electro-optical conversion of high-speed data signals. Electrical interconnects 260 and other electrical interconnects described herein may enable high-speed electrical signals to be conveyed between the component 250 and the transceiver chips 256, and other electrical interconnects described herein may be similar to the electrical interconnects 260.

[0065] Glass waveguide interconnects 252 are also positioned on the co-packaged optic substrate 248, and the glass waveguide interconnects 252 may each abut the transceiver chips. Also, the glass waveguide interconnects 252 are positioned at an edge of the co-packaged optic substrate 248. The positioning of glass waveguide interconnects 252 may enable a non-polarization maintaining optical waveguide 262 and a polarization maintaining optical waveguide 264 to connect to the transceiver chip 256 at one end and extend to the edge of the co-packaged optic substrate 248 (and to the edge of the co-packaged optic substrate 248) at another end to allow for a connection to the connector 254, which may be a glass-waveguide-to-fiber connector. This connection may enable an optical path to be formed with a laser module 214. Glass interconnects may be provided in the form of a glass substrate or an attachable glass component, and waveguides may be fabricated in the glass waveguide interconnects.

[0066] In order to facilitate a connection of fibers to the transceiver chips 256, a glass waveguide interconnect 252 is positioned between the fibers and the respective transceiver chip 256 that the fibers are being connected to. In the illustrated embodiment of FIG. 2A, one glass waveguide interconnect 252 is provided for every transceiver chip 256 that is present. A non-polarization maintaining optical waveguide 262 and a polarization maintaining optical waveguide 264 may be fabricated in each glass waveguide interconnect 252.

[0067] A laser module 214 is also positioned at and attached to the faceplate 258. A first end of a polarization maintaining optical fiber 268 is connected to the laser module 214, and a second end of the polarization maintaining optical fiber 268 is connected to the connector 254. However, laser modules may be positioned at several different locations as illustrated in FIGS.4A–4C.

[0068] Additionally, a connector 216 is positioned at and attached to the faceplate 258. The connector 216 may be a fiber-to-fiber connector. A first end of a non-polarization maintaining optical fiber 266 (e.g., a single mode fiber) is connected to the connector 216, and a second end of the non-polarization maintaining optical fiber 266 is connected to the connector 254.

[0069] FIG. 2B is a top, schematic view illustrating an assembly 246A for connecting a laser module 214A to a transceiver chip 256A, with the assembly 246A using polarization maintaining optical fibers 268A to form an optical link connecting the laser module 214A to the transceiver chip 256A. The assembly 246A includes an electrical printed circuit board 202A, which may comprise organic material. The assembly 246A includes a faceplate 258A attached to a side of the electrical printed circuit board 202A. The assembly 246A also includes a core unit assembly 245A. The core unit assembly 245A comprises a substrate 248A that is positioned at an internal location on the electrical printed circuit board 202A such that the substrate 248A is surrounded by the electrical printed circuit board 202A.

[0070] A component 250A is positioned on the substrate 248A, with the component 250A forming part of the core unit assembly 245A. The component 250A may be an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, or a memory chip. Additionally, transceiver chips 256A are positioned on the substrate 248A, and the transceiver chips 256A are attached to the component 250A using electrical interconnects 260A. The transceiver chips 256A are part of the core unit assembly 245A. The transceiver chips 256A and other transceiver chips described herein may be configured to enable electro-optical conversion of high-speed data signals. The electrical interconnect 260A and other electrical interconnects described herein may enable high-speed electrical signals to be conveyed between the component 250A and a transceiver chip 256A, and other electrical interconnects described herein may be similar to the electrical interconnect 260A. The electrical interconnect 260A is part of the core unit assembly 245A.

[0071] The substrate 248A of FIG.2B comprises a glass. While the core unit assembly 245 of FIG. 2A includes glass waveguide interconnects 252A positioned on the substrate 248A, the core unit assembly 245A of FIG.2B does not include any glass waveguide interconnects 252A. Instead, the non-polarization maintaining optical waveguide 262A and the polarization maintaining optical waveguide 264A are formed in the substrate 248A, and the entire substrate 248A may effectively serve as a larger glass waveguide interconnect. Thus, waveguides 262A, 264A are fabricated into the substrate 248A and extend from a transceiver chip 256A to the edge of the substrate 248A so that they may be connected to the connector 254A. The connector 254A may be a glass-waveguide- to-fiber connector. The waveguides 262A, 264A are part of the core unit assembly 245A.

[0072] A laser module 214A is also positioned at and attached to the faceplate 258A. A first end of a polarization maintaining optical fiber 268A is connected to the laser module 214A, and a second end of the polarization maintaining optical fiber 268A is connected to the connector 254A. However, laser modules may be positioned at several different locations as illustrated in FIGS. 4A–4C.

[0073] Additionally, a connector 216A is positioned at and attached to the faceplate 258A. The connector 216A may be a fiber-to-fiber connector. A first end of a non-polarization maintaining optical fiber 266A (e.g., a single mode fiber) is connected to the connector 216A, and a second end of the non-polarization maintaining optical fiber 266A is connected to the connector 254A. The non-polarization maintaining optical fiber 266A may be used to form an optical path with another component that does not require polarization to be maintained.

[0074] In FIG. 3, an assembly of another embodiment of the present disclosure is illustrated, with the assembly 346 providing potential benefits over the assembly 246, assembly 246A, and other assemblies. The assembly 346 may enable a laser module 314 to be connected to a core unit assembly 351 without requiring any polarization maintaining optical fibers or any other fibers to facilitate this connection. Instead of using polarization maintaining optical fibers, one or more polarization maintaining optical waveguides (e.g., polarization maintaining optical waveguide 364) may be utilized to connect the laser module 314 to the core unit assembly 351. The assembly 346 enables a connection between a laser module 314 and a transceiver chip on the core unit assembly 351 without requiring the use of any polarization-maintaining optical fibers. Polarization-maintaining optical fibers are often costly and which must be assembled so that they are positioned with an angular alignment that is highly precise. Accomplishing the high precisionrequired for angular alignment of polarization-maintaining optical fibers may increase manufacturing costs as well. Thus, the assembly 346 may be made in a more efficient and cost- effective manner.

[0075] The assembly 346 includes a glass circuit board 348, with the assembly 346 being configured to connect the laser module 314 to a transceiver chip 356 without requiring polarization maintaining optical fibers. The glass circuit board 348 includes glass material such as an alkali containing glass. The laser module 314 may be an ELSFP module.

[0076] The assembly 346 includes a core unit assembly 351. This core unit assembly 351 may include a component 350, a transceiver chip 356, and an electrical interconnect 360. The component 350 may be an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, or a memory chip. The transceiver chip 356 may be a co-packaged transceiver chip. The electrical interconnect 360 may connect the transceiver chip 356 to the component 350. In some embodiments, the core unit assembly 351 may include a portion of the glass circuit board 348. A polarization sensitive modulator may be included as part of the core unit assembly 351 and other core unit assemblies described herein. For example, the polarization sensitive modulator may be a part of the component 350 or may be connected to the component 350 on the core unit assembly 351.

[0077] The assembly 346 includes a polarization maintaining optical waveguide 364 and a non-polarization maintaining optical waveguide 362. The non-polarization maintaining optical waveguide 362 may be a single-mode glass optical waveguide in some embodiments. While only one non-polarization maintaining optical waveguide 362 and one polarization maintaining optical waveguide 364 are illustrated in FIG. 3, additional non-polarization maintaining optical waveguides and / or polarization maintaining optical waveguides may be included in other embodiments.

[0078] The polarization maintaining optical waveguide 364 and other polarization maintaining optical waveguides described herein may comprise potassium or silver (e.g., they may comprise potassium doping or silver doping) in some embodiments, but other materials may be used instead of or in addition to potassium or silver. The polarization maintaining optical waveguide 364 includes a first end and a second end. The first end of the polarization maintaining optical waveguide 364 is attached to the core unit assembly 351. For example, the first end of the polarization maintaining optical waveguide 364 may be attached to the transceiver chip 356. Thesecond end of the polarization maintaining optical waveguide 364 is connected to the laser module 314. In FIG. 3, the laser module 314 is attached to the faceplate 358, and the laser module 314 is fabricated in and positioned on the glass circuit board 348. However, the laser module 314 may be positioned at other locations as described further herein.

[0079] The non-polarization maintaining optical waveguide 362 and other non-polarization maintaining optical waveguides described herein may comprise potassium or silver (e.g., they may comprise potassium doping or silver doping) in some embodiments, but other materials may be used instead of or in addition to potassium or silver. The non-polarization maintaining optical waveguide 362 also includes a first end and a second end. The first end of the non-polarization maintaining optical waveguide 362 is attached to the core unit assembly 351. For example, the first end of the non-polarization maintaining optical waveguide 362 may be attached to the transceiver chip 356. The second end of the non-polarization maintaining optical waveguide 362 is connected to a connector 354. The connector 354 may be a glass-waveguide-to-fiber connector, and other fibers may be connected to connector 354. These fibers may be non-polarization maintaining optical fibers. The connector 354 is attached at the faceplate 358.

[0080] The polarization maintaining optical waveguide and the non-polarization maintaining optical waveguide are each fabricated in the glass circuit board 348, and the core unit assembly 351 and each of the components therein are also attached to the glass circuit board 348.

[0081] While the assembly 246 of FIG. 2A includes an electrical printed circuit board 202, assembly 346 does not include an electrical printed circuit board and instead includes a larger glass circuit board 348. However, the assembly 346 may optionally include an electrical printed circuit board in other embodiments. Also, the assembly 246 in FIG.2A includes multiple glass waveguide interconnects 252 in order to facilitate a connection between fibers and the transceiver chip 256. By contrast, the glass circuit board 348 effectively serves as the only glass waveguide interconnect in assembly 346. In FIG.2A, multiple connectors 254 that are glass-waveguide-to-fiber connectors are positioned away from locations on the faceplate 258, and connectors 216 (e.g., fiber-to-fiber connectors) are positioned at the faceplate 258. By contrast, in FIG. 3, connectors 354 that are glass-waveguide-to-fiber connectors are positioned at the faceplate 358.

[0082] As noted previously, laser modules may be positioned at various locations relative to a glass circuit board. FIGS.4A–4C are top, schematic views illustrating example assemblies 470A, 470B, 470C similar to the assembly 346 of FIG. 3, where laser modules are positioned in variouslocations relative to a glass circuit board 448. In each of the assemblies 470A, 470B, 470C, the glass circuit board 448 is rectangular in shape, the faceplate 458 is placed in contact with one side of the glass circuit board 448, and the housing 472 is placed in contact with the three other sides of the glass circuit board 448 so that the faceplate 458 and the housing 472 wrap around all four sides of the rectangularly shaped glass circuit board 448. However, the glass circuit board 448 may not have a rectangular shape in other embodiments, and the faceplate and housing may be set up differently in other embodiments.

[0083] Additionally, connectors 454 are positioned on the faceplate 458 in each of the assemblies 470A–470C. These connectors 454 are glass-waveguide-to-fiber connectors. Each of the assemblies 470A–470C has non-polarization maintaining optical waveguides 462, with a first end of these non-polarization maintaining optical waveguides 462 being attached to the core unit assembly 474 (e.g., a chip having ports 476 where non-polarization maintaining waveguides may be connected). A second end of these non-polarization maintaining optical waveguides 462 may be attached to the connectors 454. The core unit assembly 474 also includes a component 450 positioned thereon, and this component 450 may be an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, or a memory chip.

[0084] Each of the assemblies 470A–470C also includes one or more laser modules, and first ends of polarization maintaining optical waveguides 464 may be attached to the core unit assembly 474 while second ends of the polarization maintaining optical waveguides 464 are attached to a laser module (e.g., at a port on the laser module). In each of the assemblies 470A–470C, the laser modules are positioned at different locations. In the assembly 470A of FIG.4A, the laser modules 414A, 414B are positioned on the glass circuit board 448, with the laser modules 414A, 414B abutting the faceplate 458. The laser modules 414A, 414B of assembly 470A may be attached to the glass circuit board 448 and / or the faceplate 458.

[0085] The assembly 470B of FIG.4B is generally similar to the assembly 470A of FIG. 4A. However, in the assembly 470B of FIG. 4B, the laser module 414C is positioned on and attached to the housing 472 opposite the faceplate 458, with the laser module 414C abutting the glass circuit board 448. This may enable the polarization maintaining optical waveguides 464 to extend all the way to the laser module 414C. The laser module 414C may be attached to the side of the glass circuit board 448. As a result of this positioning for the laser module 414C, the positioning of the non-polarization maintaining optical waveguides 462 and the polarization maintaining opticalwaveguide 464 are different in the assembly 470B relative to how these waveguides are positioned in the assembly 470A of FIG.4A.

[0086] The assembly 470C of FIG.4C is generally similar to the assembly 470A of FIG. 4A. However, in the assembly 470C of FIG. 4C, the laser module 414D is positioned on the glass circuit board 448 at a position that is separated from the housing 472 and the faceplate 458. At this location, the laser module 414D is separated from the housing 472 and the faceplate 458 by a distance. As a result of this new positioning for the laser module 414D, the positioning of the non- polarization maintaining optical waveguide 462 and the polarization maintaining optical waveguide 464 are different in the assembly 470C relative to how these optical waveguides are positioned in the assembly 470A of FIG.4A and the assembly 470B of FIG.4B. The positions for the laser modules 414A–414D are merely exemplary, and other positions may be used in other embodiments.

[0087] In FIG. 5, a top, schematic view of an example assembly 578 is illustrated where a polarization maintaining optical waveguide 564 is illustrated that acts as an optical splitter. The assembly 578 includes a polarization maintaining optical waveguide 564 and a core unit assembly 556 positioned on a glass circuit board 548. The core unit assembly 556 may be similar to others described herein. The polarization maintaining optical waveguide 564 includes a first segment 564A that is split into four separate segments 564B. Each of the segments 564B are connected to the core unit assembly 556 (e.g., at a transceiver chip of the core unit assembly 556). The first segment 564A may extend to a laser module (not shown) so that the first segment 564A is connected to the laser module. By having the polarization maintaining optical waveguide 564 split from one segment 564A into four separate segments 564B, the polarization maintaining optical waveguide 564 may effectively include a 1-to-4 power splitter that is a passive optical splitter. Additionally or alternatively, an active switching element may be used in glass to distribute laser power to different modulators in the core unit assembly 556. The active switching element may utilize electric power in some embodiments to operate the active switching element and to direct the laser power as desired. By including a splitter or an active switching element, external laser power may be coupled to the core unit assembly 556 or a transceiver chip therein in four different locations. The pitch (e.g., the distance between central axies of adjacent segments 564B) between the parallel laser channels where they connect to the core unit assembly 556 may be as little as about 20 microns, but other pitches may be used.

[0088] Sharing laser power between different channels before coupling to the core unit assembly 556 may reduce the power density at the polarization maintaining optical waveguide 564, at the interface between the segments 564A–564D and the core unit assembly 556, at transceiver optical waveguides that may be smaller than other optical waveguides, and other materials. Thus, polarization maintaining optical waveguide 564 may be made with relatively small dimensions of about 400 nanometers or less in thickness and / or width. In case an optical adhesive is in the interface for evanescent coupling, edge-coupling, or grating coupling between glass and chip, the power level may be reduced below the damage threshold and make the interface reliable and low loss. In some embodiments, optical splitters may be implemented in non- polarization maintaining optical waveguides.

[0089] Methods for forming polarization maintaining optical waveguides within glass are also contemplated. FIG.6 is a flow chart illustrating one example method 682, and FIG.7 is a schematic view illustrating the various operations of the method 682 of FIG.6.

[0090] At operation 684 of FIG. 6 and operation 784 depicted in FIG. 7, one or more masks 794 may be positioned on the glass circuit board material 748 at a surface 748A of the glass circuit board material 748. The mask(s) 794 may each be thin film masks. The mask(s) 794 may be positioned on the surface 748A so that at least one exposed surface area 796 is left uncovered by the mask(s) 794 on the surface 748A of the glass circuit board material 748. The mask(s) 794 may be positioned before any ion-exchange cycles are performed in some embodiments.

[0091] At operation 686 of FIG. 6 and operation 786 depicted in FIG.7, one or more thermal ion-exchange cycles may be performed with a first material. The first material may comprise silver in some embodiments, but the first material may comprise other materials instead such as potassium. The first material may be provided in the form of a salt melt 798 (that may optionally include silver nitrate (AgNO3)). Due to the presence of the mask(s) 794, most of the waveguide material 701 that is exchanged to the glass circuit board material 748 is added proximate to the exposed surface area 796. Thus, the shape of the mask(s) 794 and the exposed surface area 796 may control the shape of the material that is exchanged and the eventual shape of optical waveguides that are formed.

[0092] At operation 688 of FIG. 6 and operation 788 depicted in FIG. 7, the mask(s) 794 are removed from the glass circuit board material 748. At operation 690 of FIG. 6 and operation 790 depicted in FIG. 7, one or more additional ion-exchange cycles are performed once the mask(s)794 are removed. The additional ion-exchange cycle(s) may be performed using thermal ion- exchange with a material comprising sodium. For example, the material used in thermal-ion exchange may be provided in the form of a salt melt 703 and may optionally include sodium nitrate (NaNO3). After operation 688 and operation 788, modified waveguide material 705 may be present in the glass circuit board material 748.

[0093] At operation 692 of FIG. 6 and operation 792 depicted in FIG. 7, singulation may be performed. During singulation, the glass circuit board material 748 may be separated into smaller sections (e.g., through cutting). Thus, an assembly 746 including the modified waveguide material 705 within a glass circuit board 748B may be separated from other sections 748C of the glass circuit board material as indicated by the gaps 709.

[0094] Where the method 682 of FIG. 6 is performed, the refractive index profile at formed optical waveguides may be elliptical in shape. This shape may occur due to isotropic diffusion on both sides under the masks 794 and the depth of the glass circuit board material 748. For a single- mode waveguide, the refractive index may be about 0.003 to about 0.01 higher than the refractive index in the glass circuit board material 748. Additionally, for single-mode optical waveguides that are formed, fiber coupling losses to the optical waveguides may be in the order of about 0.1 decibels to about 0.6 decibels. The specific amount of fiber coupling losses may be dependent on the optical waveguide design, the resulting refractive index, and a fundamental mode for the optical waveguide. The glass circuit board material used in method 682 may be provided in the form of a glass waveguide interconnect.

[0095] Another example method 811 for forming optical waveguides within a glass circuit board is illustrated in FIG.8. At operation 813, a glass circuit board material is provided, and this material may include an alkali containing glass. At operation 815, a first ion-exchange cycle is completed using a first material, and this first ion-exchange cycle is completed at a first temperature. At operation 817, a second ion-exchange cycle is completed using a second material, and this second ion-exchange cycle is completed at a second temperature. In some embodiments, the first material may comprise potassium. For example, the first material may be potassium nitrate (KNO3). Additionally, the second material may comprise silver. For example, the second material may be silver nitrate (AgNO3). The second temperature may also be below the first temperature. For example, the first temperature may be between about 350 degrees Celsius to about 450 degrees Celsius when ion-exchange cycles are performed with potassium based material, and the secondtemperature may be about 350 degrees Celsius or less when ion-exchange cycles are performed with silver based material. In some embodiments, the first ion-exchange cycle may be used to form polarization maintaining optical waveguides and the second ion-exchange cycle may be used to form non-polarization maintaining optical waveguides, with polarization maintaining optical waveguides comprising potassium and with non-polarization maintaining optical waveguides comprising silver. While the method 811 includes three different operations, some of these operations may be omitted in other embodiments. For example, operation 815 may be omitted in some embodiments (see, e.g., process flow 911A of FIG. 9A). Furthermore, additional operations may be performed, and the operations may be performed in different orders. For example, more than one first ion-exchange cycle or more than second ion-exchange cycle may be performed.

[0096] FIGS. 9A–9D are schematic views illustrating the various operations of the method 811 of FIG.8, with the process flows 911A–911D for the formation of assemblies being illustrated. Looking first at FIG. 9A, a process flow 911A is illustrated where only one type of optical waveguide is used. At stage 913A, the glass circuit board 948 is provided. This glass circuit board 948 and other glass circuit boards described herein may include an alkali containing glass. The process flow 911A also includes stage 917A. At stage 917A, one or more ion-exchange cycles are completed using a material, and these ion-exchange cycle(s) are completed at a temperature of about 350 degrees Celsius or less. The material comprises silver in the illustrated embodiment, but other materials such as a potassium-based material may be deposited instead of a silver-based material in other embodiments. After stage 917A is performed, silver optical waveguides 919A, 919B may be formed within the glass circuit board 948, and these optical waveguides 919A, 919B may be polarization maintaining optical waveguides or non-polarization maintaining optical waveguides.

[0097] Looking now at FIG. 9B, a process flow 911B is illustrated where two different types of optical waveguides are used. At stage 913B, the glass circuit board 948 is provided. At stage 915B, one or more first ion-exchange cycles are completed using a first material, and these first ion-exchange cycle(s) are completed at a first temperature. The first temperature may be between about 350 degrees Celsius to about 450 degrees Celsius. The first material comprises potassium in the illustrated embodiment, but other materials may be used in other embodiments. After stage 915B is complete, a potassium polarization maintaining optical waveguide 921A is formed withinthe glass circuit board 948. However, the waveguide that is formed in stage 915B may be a non- polarization maintaining optical waveguide in other embodiments.

[0098] At stage 917B, one or more second ion-exchange cycles is completed using a second material, and these second ion-exchange cycle(s) are completed at a second temperature. The second ion-exchange cycle(s) may be performed after the first ion-exchange cycle(s) are performed. The second material is different from the first material. The second material is silver in the illustrated process flow 911B, but the second material may be a different material in other embodiments. Additionally, the second temperature is different from the first temperature. In the illustrated embodiment, the second temperature is lower than the first temperature such that the temperature for the potassium ion-exchange cycle(s) is greater than the temperature for the silver ion-exchange cycle(s). The second temperature is about 350 degrees Celsius or less. However, the materials and temperatures may be different in other embodiments. After stage 917B is complete, a silver polarization maintaining optical waveguide 919C may be formed within the glass circuit board 948. However, the waveguide that is formed in stage 917B may be a non-polarization maintaining optical waveguide in other embodiments. By completing stage 917B after stage 915B, exposure of the silver polarization maintaining optical waveguide 919C to temperatures above about 350 degrees may be avoided.

[0099] Turning now to FIG. 9C, a process flow 911C is illustrated where two different types of polarization maintaining optical waveguides are used and where the geometries for these polarization maintaining optical waveguides are made different from each other. The process flow 911C is generally the same as the process flow 911B of FIG. 9B. Stages 913C and 917C may be performed in a similar manner relative to stages 913B and 917B of FIG. 9B, with the silver polarization maintaining optical waveguide 919D of FIG. 9C that is formed generally being the same as the silver polarization maintaining optical waveguide 919C of FIG. 9B. However, the geometry of the potassium polarization maintaining optical waveguide 921B that is formed at stage 915C of FIG. 9C is different than the geometry of the potassium polarization maintaining optical waveguide 921A that is formed at stage 915B of FIG.9B. The geometry of the optical waveguides may be controlled by using masks to cover different portions of the surface of the glass circuit board, leaving an exposed surface area where optical waveguide formation may generally occur. The process flow 911C may be used to form non-polarization maintaining optical waveguides in some embodiments.

[0100] In FIG.9D, a process flow 911D is illustrated where two different types of polarization maintaining optical waveguides are used and where the geometries for these polarization maintaining optical waveguides are made different from each other. At stage 913D, the glass circuit board 948 is provided. At stage 915D, first ion-exchange cycle(s) are completed using a first material, and the first ion-exchange cycle(s) are completed at a first temperature. Stage 915D may generally be performed in a manner similar to stages 915B and 915C of FIGS. 9B and 9C respectively. However, after stage 915D is complete, a first potassium polarization maintaining optical waveguide 921C and a second potassium polarization maintaining optical waveguide 921D are formed within the glass circuit board 948. As noted previously, positioning of masks may effectively control the shape of the optical waveguides.

[0101] At stage 917D, second ion-exchange cycle(s) are completed using a second material, and the second ion-exchange cycle(s) are completed at a second temperature. Stage 917D is generally the same as stages 917A, 917B, and 917C of FIGS. 9A–9C. After stage 917D is complete, a first silver polarization maintaining optical waveguide 919E and a second silver polarization maintaining optical waveguide 919F are formed within the glass circuit board 948. The process flow 911D may be used to form non-polarization maintaining optical waveguides in addition to or instead of polarization maintaining optical waveguides in some embodiments.

[0102] For each of the processes represented in FIGS. 9A–9D, additional operations may be performed. For example, one or more masks may be added to control the shape of waveguides as described herein. Additionally, as described herein, one or more ion-exchange cycles may be also performed using a material comprising sodium such as sodium nitrate (NaNO3). Singulation may also be performed to cut the glass circuit board 948. In some embodiments, the potassium polarization maintaining optical waveguides may be replaced by potassium stress elements that are capable of controlling polarization. The glass circuit boards used in method 811 of FIG.8 and in the processes depicted in FIGS. 9A–9D may be provided in the form of a glass waveguide interconnect in some embodiments.

[0103] FIG. 10 is a side, schematic view illustrating an assembly 1023 with silver-based polarization maintaining optical waveguides 1019 comprising silver formed within a glass circuit board 1048, and FIG. 11 is a plot 1125 illustrating an example index profile for a portion of the assembly 1023 of FIG. 10 proximate to one of the polarization maintaining optical waveguides 1019. The silver-based polarization maintaining optical waveguides 1019 are positioned proximateto the surface 1048A of the glass circuit board 1048, and the surface 1048A of the glass circuit board 1048 corresponds to a Y-position of around 251 micrometers in the plot 1125 of FIG. 11. While the optical waveguides 1019 are silver-based polarization maintaining optical waveguides in FIG.10, these may instead be silver-based non-polarization maintaining optical waveguides in other embodiments.

[0104] The silver-based polarization maintaining optical waveguides 1019 generally have lower insertion losses and polarization-dependent losses compared to potassium-based polarization maintaining optical waveguides. For silver-based polarization maintaining optical waveguides having a propagation length of about 25 millimeters, the average insertion loss may be about 1.048 decibels, the insertion loss may have a standard deviation of about 0.08 decibels, and the minimum insertion loss may be about 0.95 decibels. Additionally, for silver-based polarization maintaining optical waveguides having a propagation length of about 25 millimeters, the polarization-dependent losses may be about 0.086 decibels. However, these values may be changed where the silver-based polarization maintaining optical waveguides have a different geometry, a different propagation length, etc. or where a different substrate is used.

[0105] In the plot 1125, the area 1127 generally corresponds to the locations where the polarization maintaining optical waveguide 1019 is located. The refractive index may be about 1.492 or higher within the area 1127. At a center 1129 of the area 1127 (which corresponds to a central location in the polarization maintaining optical waveguide 1019), the refractive index may be about 1.497. The plot 1125 shows that the refractive index (or the n-value) is around 1.491 at areas 1131 positioned away from the area 1127 corresponding to the polarization maintaining optical waveguide 1019. Areas 1131 may correspond to the glass material within the glass circuit board 1048. Thus, the refractive index at the center 1129 is higher than the refractive index at areas 1131 by about 0.006 or more.

[0106] FIG. 12 is a side, schematic view illustrating an assembly 1223 with potassium-based polarization maintaining optical waveguides 1221 formed within a glass circuit board 1248. The potassium-based polarization maintaining optical waveguides 1221 are formed proximate to the surface 1248A. Where the potassium-based polarization maintaining optical waveguides 1221 have a propagation length of about 25 millimeters, the average insertion loss may be about 1.108 decibels, the insertion loss may have a standard deviation of about 0.06 decibels, and the minimum insertion loss may be about 1.03 decibels. Additionally, where the potassium-based polarizationmaintaining optical waveguides 1221 have a propagation length of about 25 millimeters, the polarization-dependent losses may be about 0.526 decibels. However, these values may be changed where the potassium-based polarization maintaining optical waveguides have a different geometry, a different propagation length, etc. or where a different substrate is used.

[0107] FIG.13 is a side, schematic view illustrating an assembly 1323 comprising silver-based polarization maintaining optical waveguides 1319 formed within a glass circuit board 1348B. The glass circuit board 1348B comprises a different glass material than the glass circuit boards 1048 of FIG. 10 and the glass circuit board 1248 of FIG. 12. The silver-based polarization maintaining optical waveguides 1319 are formed proximate to a surface 1348A of the glass circuit board 1348B. For silver-based polarization maintaining optical waveguides 1319 having a propagation length of about 25 millimeters, the average insertion loss may be about 0.766 decibels, the insertion loss may have a standard deviation of about 0.11 decibels, and the minimum insertion loss may be about 0.68 decibels. Additionally, for silver-based polarization maintaining optical waveguides 1319 having a propagation length of about 25 millimeters, the polarization-dependent losses may be about 0.080 decibels. However, these values may be changed where the silver-based polarization maintaining optical waveguides 1319 have a different geometry, a different propagation length, etc. or where a different substrate is used. Each of the assemblies 1023, 1123, 1323 have strong levels for insertion losses and polarization-dependent losses, and the assemblies 1023, 1123, 1323 may be formed in a cost-efficient manner. While the optical waveguides 1319 are silver-based polarization maintaining optical waveguides in FIG. 13, these may instead be silver-based non-polarization maintaining optical waveguides in other embodiments.

[0108] FIG. 14 is a plot 1433 illustrating power output for a polarization maintaining optical waveguide similar to those described herein over the course of 37 days. The polarization maintaining optical waveguide included silver and was made through a silver ion exchange process with a glass circuit board. The polarization maintaining optical waveguide was subjected to a high- power test and subjected to 250 milliwatts of optical transmission power for over 30 days. As illustrated by the plot 1433 of FIG. 14, the power output for the polarization maintaining optical waveguide remained stable over this 30 day period without performance degradation over time. The power oscillation illustrated from the plot 1433 arose due to changes in power at the laser module.

[0109] Additional tests were performed to evaluate the polarization extinction ratio and how this ratio is impacted by other factors like an input polarization angle, angular misalignment, and propagation length for polarization maintaining optical waveguides. FIG. 15 is a schematic view illustrating an example testing assembly 1583 that was used. The testing assembly 1583 comprises a laser 1557 configured to generate a laser beam 1559. The testing assembly 1583 also includes an isolator 1561, a depolarizer 1563, a polarizing beam splitter 1565, a polarization maintaining optical fiber coupler 1567, a polarization maintaining optical fiber rotator 1569, a device-under- test (DUT) 1571, a first collimating lens 1573, a second collimating lens 1575, a polarizer 1577, a rotating member 1579, a photodetector 1581, and a polarization maintaining optical fiber 1585. The DUT 1571 includes a polarization maintaining optical waveguide forming an optical path with the polarization maintaining optical fiber 1585. The isolator 1561 may be configured to allow the transmission of light in only one direction. The polarization maintaining optical fiber rotator 1569 is configured to cause rotation of the polarization maintaining optical fiber 1585 and the polarization maintaining optical fiber coupler 1567 so that the polarization maintaining optical fiber 1585 and the polarization maintaining optical waveguide within the DUT 1571 are used at different input polarization angles, and the polarization extinction ratio may be evaluated based on data obtained from the photodetector 1581 for various input polarization angles.

[0110] FIG. 16 is a line graph 1643 illustrating polarization extinction ratio as a function of input polarization angle for polarization maintaining optical waveguides having different propagation lengths with this data being obtained using the testing assembly 1583 illustrated in FIG. 15. Plotline 1643A illustrates data for a polarization maintaining optical waveguide possessing a propagation length of about 25 millimeters. Plotline 1643B illustrates data for a polarization maintaining optical waveguide possessing a propagation length of about 50 millimeters. Plotline 1643C illustrates data for a polarization maintaining optical waveguide possessing a propagation length of about 75 millimeters. As illustrated, the polarization extinction ratio is generally the highest for plotline 1643C (corresponding to propagation length of about 75 millimeters), the polarization extinction ratio is generally the second highest for plotline 1643A (corresponding to propagation length of about 25 millimeters), and the polarization extinction ratio is generally the lowest for plotline 1643B (corresponding to propagation length of about 50 millimeters). Additionally, the polarization extinction ratio is generally the highest when the input polarization angle is around 0 degrees, 90 degrees, or 180 degrees. The data represented byplotlines 1643A–1643C was obtained using straight polarization maintaining optical waveguides comprising silver and using a swept optical light source at wavelength of about 1310 nanometers with a linear polarization angle used at the input.

[0111] FIG. 17 is a line graph 1745 illustrating polarization extinction ratio as a function of angular misalignment for polarization maintaining optical waveguides having different propagation lengths with this data being obtained using the testing assembly 1583 illustrated in FIG. 15. The first plotline 1745A illustrates data for a polarization maintaining optical waveguide possessing a propagation length of about 25 millimeters. The second plotline 1745B illustrates data for a polarization maintaining optical waveguide possessing a propagation length of about 50 millimeters. The third plotline 1745C illustrates data for a polarization maintaining optical waveguide possessing a propagation length of about 75 millimeters. As illustrated by the plotlines 1745A–1745C, varying the propagation length for polarization maintaining optical waveguides may substantially impact the polarization extinction ratio. The second plotline 1745B (for polarization maintaining optical waveguide having propagation length of about 50 millimeters) had the lowest polarization extinction ratio, the first plotline 1745A (for polarization maintaining optical waveguide having propagation length of about 25 millimeters) had the second highest polarization extinction ratio of the three plotlines, and the third plotline (for polarization maintaining optical waveguide having propagation length of about 75 millimeters) had the highest polarization extinction ratio of the three plotlines. In some embodiments, the polarization extinction ratio may be maintained at a level that is higher than the first plotline 1745A even when the propagation length is increased to somewhere between about 75 millimeters and about 100 millimeters. As such, the polarization maintaining optical waveguides may be made so that they have a propagation length between about 75 millimeters and about 100 millimeters to maintain a high polarization extinction ratio. However, in other embodiments, the polarization maintaining optical waveguides may be used with a propagation length between about 3 millimeters and about 500 millimeters. The optimal propagation length that maximizes the polarization extinction ratio may depend upon the beat length for a polarization maintaining waveguide and other factors.

[0112] As shown by the third plotline 1745C, a polarization extinction ratio of about 20 decibels or more, about 23 decibels or more, or about 30 decibels or more may be accomplished with an angular misalignment of less than about three degrees. In fact, the polarization extinction ratio is about 37.5 decibels for the plotline 1745C when the angular misalignment is about threedegrees, and the polarization extinction ratio increases further for the plotline 1745C as the angular misalignment is reduced.

[0113] Both the polarization extinction ratio and sensitivity to angular misalignment of polarization maintaining optical waveguides are dependent on a waveguide propagation length for the polarization maintaining optical waveguides. These polarization maintaining optical waveguides may possess a relatively low birefringence and a relatively high beat length of about 100 millimeters. This relatively large beat length combined with the ability to control waveguide propagation lengths down to tens of microns enables precise phase delays to be accomplished between two polarization modes for a waveguide. The polarization extinction ratio indicates the power of the strongest polarization mode relative to the weakest polarization mode.

[0114] In some embodiments, control of phase delay may be used to prepare circular or elliptical polarization states from a linear input. These polarization states may be accomplished by coupling a polarization maintaining optical waveguide at an angle such that both the slow and fast axes of the polarization maintaining optical waveguide are excited (e.g., at an angle of about 30 degrees, at an angle of about 45 degrees, etc.). From this input, arbitrary states of polarization may be generated in principle. The polarization maintaining optical waveguides may operate in a first polarization mode along the slow axis and a second polarization mode along the fast axis, and the slow and fast axes are perpendicular to each other. In some embodiments, the polarization states may be accomplished by coupling the polarization maintaining optical waveguide at an angle such that both the slow and fast axes of the polarization maintaining optical waveguide are equally excited.

[0115] In some embodiments, polarization maintaining optical waveguides may be provided with high birefringence sections and low birefringence sections. Examples where this is implemented are illustrated in FIGS. 18A–18C. FIGS. 18A–18B are side, schematic views illustrating assemblies 1823A, 1823B having polarization maintaining optical waveguides formed within glass circuit boards 1848 at different positions. In FIG.18A, the assembly 1823A includes low birefringence sections 1819A and a high birefringence section 1847A, with sections 1819A, 1847A each being at least partially embedded within the glass circuit board 1848. The desired phase shift may be accomplished by transitioning one of the waveguides from a low birefringence ion-exchange profile to a high birefringence ion-exchange profile and then back again to a low birefringence ion-exchange profile.

[0116] In FIG.18B, the assembly 1823B includes low birefringence sections 1819B and a high birefringence section 1847B. The high birefringence section 1847B is positioned on the surface of the glass circuit board 1848 and is not embedded within the glass circuit board 1848, but the low birefringence sections 1819B are embedded within the glass circuit board 1848. The assemblies 1823A, 1823B are merely two different examples of how high birefringence sections and low birefringence sections may be arranged, and other arrangements may also be used for these sections. In the assembly 1823B, the desired phase shift is accomplished by producing the high birefringence section 1847B above one or more of the low birefringence sections 1819B, and the high birefringence section 1847B interacts with the evanescent field to increase birefringence at areas proximate to the high birefringence section 1847B.

[0117] In the assemblies 1823A, 1823B, the low birefringence sections 1819A, 1819B are each distinct polarization maintaining optical waveguides that possess low birefringence along their entire lengths, and the high birefringence sections 1847A are each distinct polarization maintaining optical waveguides possessing high birefringence along their entire lengths. However, a single polarization maintaining optical waveguide may have a high birefringence section and a low birefringence section in some embodiments, and an example of this is illustrated in the assembly 1823C of FIG. 18C.

[0118] FIG. 18C illustrates a top, schematic view of another assembly 1823C comprising polarization maintaining optical waveguides 1849A, 1849B formed within a glass circuit board 1848. The first polarization maintaining optical waveguide 1849A includes a high birefringence section 1851B positioned between a first low birefringence section 1851A and a second low birefringence section 1851C. By contrast, the second polarization maintaining optical waveguide 1849B includes only one low birefringence section 1851D and includes no high birefringence sections, with the birefringence level generally remaining about the same along the entire length of the second polarization maintaining optical waveguide 1849B. Different arrangements and combinations may be used for high and low birefringence sections in other embodiments, and the assembly 1823C is merely provided as an example. Additionally, the levels of birefringence in the different sections may be different in other embodiments, and sections may be provided with three or more different birefringence levels in some embodiments.

[0119] By varying the birefringence between the sections, polarization maintaining optical waveguides may be formed with the desired phase shifts without requiring a change in propagationlength for the polarization maintaining optical waveguides. For example, the polarization maintaining optical waveguide 1849A may have a high phase delay, and the polarization maintaining optical waveguides 1849B may have a low phase delay relative to the polarization maintaining optical waveguide 1849A.

[0120] Precisely controlling phase delay in polarization maintaining optical waveguides may allow these optical waveguides to have a very low sensitivity to angular misalignment. Precise control of phase delay may also be accomplished by manufacturing a polarization maintaining optical waveguide so that it has a propagation length that is half of an integer multiple of a beat length (e.g., 0.5 times the beat length, 1.0 times the beat length, 1.5 times the beat length, 2.0 times the beat length, etc.). Other methods may be used to control birefrigence such as engineering a stress profile that increases birefringence.

[0121] FIG. 19A is a line graph 1953 illustrating the polarization extinction ratio when different waveguide lengths are used, with the waveguide lengths stated in terms of the waveguide length divided by the beat length. FIG. 19B is an enhanced view 1953A of the line graph 1953 of FIG. 19 that focuses on waveguide lengths ranging between 0.95 times the beat length and 1.00 times the beat length. Thus, this focuses on areas with a length ratio value (as defined below) of between 0.95 and 1.00.

[0122] Plotline 1955A illustrates data occurring when the angular misalignment is about 1 degree for a polarization maintaining optical waveguide, plotline 1955B illustrates data occurring when the angular misalignment is about 2 degrees for a polarization maintaining optical waveguide, plotline 1955C illustrates data occurring when the angular misalignment is about 3 degrees for a polarization maintaining optical waveguide, plotline 1955D illustrates data occurring when the angular misalignment is about 4 degrees for a polarization maintaining optical waveguide, and plotline 1955E illustrates data occurring when the angular misalignment is about 5 degrees for a polarization maintaining optical waveguide. As the angular misalignment is reduced, the polarization extinction ratio increases.

[0123] The polarization maintaining optical waveguides may each define a length and a beat length. A length ratio value may be defined as the propagation length divided by the beat length, and the polarization maintaining optical waveguides may be designed and manufactured so that the length ratio value remains around about 0.50 or about 1.00. For example, the polarization maintaining optical waveguides may be designed and manufactured so that the length ratio valueis between about 0.45 and about 0.55 or between about 0.95 and 1.05. As another example, the polarization maintaining optical waveguides may be designed and manufactured so that the length ratio value is between about 0.48 and about 0.52 or between about 0.98 and 1.02. By keeping the length ratio value at these levels, the polarization extinction ratio may be maintained at a high level. For example, a polarization maintaining optical waveguide may have a polarization extinction ratio of about 43 decibels or more when the angular misalignment is less than about 3 degrees where the length ratio value is between about 0.48 and about 0.52 or between about 0.98 and 1.02. As the length ratio gets even closer to 0.50 or 1.00 (e.g., between about 0.49 and 0.51 or between about 0.99 and 1.01), the polarization extinction ratios drastically increase.

[0124] In FIG.19B, an enhanced view is illustrated of length ratio values about 0.95 and 1.00 for the purposes of explanation. However, the polarization extinction ratios for each of the plotlines 1955A–1955E may be similar at length ratio values ranging from 0.45 to 0.50. Additionally, the polarization extinction ratios for each of the plotlines 1955A–1955E may be similar at length ratio values ranging from 0.50 to 0.55, but the polarization extinction ratios may decrease as the length ratio values increase from 0.50 to 0.55 and the polarization extinction ratios for each of the plotlines 1955A–1955E at a length ratio value of about 0.55 may be similar to the polarization extinction ratios at a length ratio value of about 0.95. Furthermore, the polarization extinction ratios for each of the plotlines 1955A–1955E may be similar at length ratio values ranging from 1.00 to 1.05, but the polarization extinction ratios may decrease as the length ratio values increase from 1.00 to 1.05 and the polarization extinction ratios for each of the plotlines 1955A–1955E at a length ratio value of about 1.05 may be similar to the polarization extinction ratios at a length ratio value of about 0.95. The plotlines 1955A–1955E represent data for straight optical waveguides.

[0125] FIG. 20 is a flow chart illustrating an example method 2000 for making an integrated glass waveguide assembly. At operation 2002, one or more polarization maintaining optical waveguides are fabricated in a glass circuit board. Each polarization maintaining optical waveguide may include a first end and a second end.

[0126] At operation 2004, non-polarization maintaining optical waveguides are fabricated in the glass circuit board. Each non-polarization maintaining optical waveguide may include a first end and a second end. The non-polarization maintaining optical waveguide may be a single-modeglass waveguide in some embodiments. In some embodiments, waveguides may instead be fabricated in a glass waveguide interconnect.

[0127] At operation 2006, the core unit assembly is attached to the glass circuit board. The core unit assembly may include a component, and this component may be an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, or a memory chip. In some embodiments, the core unit assembly may also comprise a transceiver chip (e.g., a co- packaged transceiver chip) and an electrical interconnect, and the transceiver chip may be attached to the component using the electrical interconnect.

[0128] At operation 2008, the core unit assembly is connected to the polarization maintaining optical waveguide and the non-polarization maintaining optical waveguide. Where a transceiver chip is included in the core unit assembly, the first end of the polarization maintaining optical waveguide and the first end of the non-polarization maintaining optical waveguide may be connected to the transceiver chip.

[0129] At operation 2010, a laser module is attached to the polarization maintaining optical waveguide. The second end of the polarization maintaining optical waveguide may be attached to the laser module. Additionally, at operation 2012, a glass-waveguide-to-fiber connector is attached to the non-polarization maintaining optical waveguide. The second end of the non-polarization maintaining optical waveguide may be attached to the glass-waveguide-to-fiber connector.

[0130] FIG. 21 is a flow chart illustrating an example method 2100 for making an integrated glass waveguide assembly. At operation 2102, first ion-exchange cycle(s) are completed using a first material, and the first ion-exchange cycle(s) are completed at a first temperature. The first material may comprise silver or potassium in some embodiments, but other materials may be used in other embodiments.

[0131] At operation 2104, second ion-exchange cycle(s) are completed using a second material, and the second ion-exchange cycle(s) are completed at a second temperature. The second ion-exchange cycle(s) may be performed after the first ion-exchange cycle(s) are performed. The second material is different from the first material, and the second temperature is different from the first temperature. The second material may comprise silver or potassium in some embodiments, but other materials may be used in other embodiments. In some embodiments, the first material may comprise potassium, the second material may comprise silver, and the first temperature maybe higher than the second temperature. However, the materials and temperatures may be different in other embodiments.

[0132] FIG. 22 is a flow chart illustrating an example method 2200 for making an integrated glass waveguide assembly. At operation 2202, one or more masks are positioned on a surface of a glass circuit board. The mask(s) may be positioned on the surface so that at least one exposed surface area is left uncovered by the mask(s) on the surface glass circuit board. The mask(s) may be positioned before any ion-exchange cycles are performed in some embodiments.

[0133] At operation 2204, one or more ion-exchange cycles are completed. Due the presence of the mask(s), most of the material that is exchanged to the glass circuit board is added proximate to the exposed surface area. Thus, the shape of the mask(s) and the exposed surface area may control the shape of the material that is exchanged and the eventual shape of optical waveguides that are formed.

[0134] At operation 2206, the mask(s) are removed from the glass circuit board. At operation 2208, one or more additional ion-exchange cycle(s) are performed once the mask(s) are removed. The additional ion-exchange cycle(s) may be performed using a thermal ion-exchange using a material comprising sodium. For example, the material may be provided in the form of a salt melt that may optionally include sodium nitrate (NaNO3).

[0135] The methods 2000, 2100, 2200 of FIGS. 20–22 may be used to form the polarization maintaining optical waveguides and / or the non-polarization maintaining optical waveguides described in different embodiments herein. The methods 2000, 2100, 2200 of FIGS. 20–22 are merely exemplary. In other embodiments, the order of operations within the methods 2000, 2100, 2200 may be adjusted. For example, some of the operations may be performed simultaneously. Additionally, operations within the methods 2000, 2100, 2200 may be omitted in some embodiments, and additional operations may be added to methods 2000, 2100, 2200 in other embodiments. In some embodiments, some or all of the methods 2000, 2100, 2200 may be combined together to form a single method. CONCLUSION

[0136] Many modifications and other embodiments set forth herein will come to mind to one skilled in the art to which these embodiments 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 are not to be limited to the specific embodiments disclosed and that modificationsand other embodiments are intended to be included within the scope of the invention. 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 invention. 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 invention. 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 IS:

1. An integrated glass waveguide assembly comprising: a core unit assembly comprising: a substrate; a transceiver chip attached to the substrate; and a polarization maintaining optical waveguide comprising a first end and a second end, wherein the first end is connected to the transceiver chip, wherein the second end is positioned proximate to an edge of the substrate, wherein the second end is configured to be connected to a polarization maintaining fiber to form an optical path with a laser module. 2 The integrated glass waveguide assembly of claim 1, further comprising: the polarization maintaining fiber.

3. The integrated glass waveguide assembly of any of claims 1 or 2, further comprising: the laser module. 4 The integrated glass waveguide assembly of claim 3, further comprising: an electrical printed circuit board, wherein the laser module is attached to the electrical printed circuit board.

5. The integrated glass waveguide assembly of any of claims 1–4, wherein the substrate comprises glass, and wherein the polarization maintaining optical waveguide is fabricated into the substrate.

6. The integrated glass waveguide assembly of any of claims 1–4, wherein the core unit assembly further comprises a waveguide interconnect comprising glass, wherein the waveguide interconnect is attached to the substrate, and wherein the polarization maintaining optical waveguide is fabricated into the waveguide interconnect.

7. The integrated glass waveguide assembly of any of claims 1–6, further comprising: a glass-waveguide-to-fiber connector, wherein the second end is directly connected to the glass-waveguide-to-fiber connector, and wherein the glass-waveguide-to-fiber connector is directly connected to the polarization maintaining fiber.

8. The integrated glass waveguide assembly of any of claims 1–4, further comprising: a non-polarization maintaining fiber, wherein the core unit assembly further comprises a non-polarization maintaining optical waveguide, wherein one end of the non-polarization maintaining optical waveguide is connected to the transceiver chip, wherein another end of the non-polarization maintaining optical waveguide is positioned proximate to the edge of the substrate and is connected to the non- polarization maintaining fiber to form a second optical path with another component.

9. The integrated glass waveguide assembly of claim 8, wherein the substrate comprises glass, and wherein the non-polarization maintaining optical waveguide is fabricated into the substrate.

10. The integrated glass waveguide assembly of claim 8, wherein the core unit assembly further comprises a waveguide interconnect comprising glass, wherein the waveguide interconnect is attached directly or indirectly to the substrate, and wherein the non-polarization maintaining optical waveguide is fabricated into the waveguide interconnect.

11. The integrated glass waveguide assembly of any of claims 1–10, wherein the core unit assembly comprises a first component and an electrical interconnect, wherein the first component comprises at least one of an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, or a memory chip, and wherein the electrical interconnect connects the transceiver chip to the first component.

12. An integrated glass waveguide assembly comprising: a glass circuit board;a core unit assembly comprising a transceiver chip; at least one polarization maintaining optical waveguide, wherein each polarization maintaining optical waveguide of the at least one polarization maintaining optical waveguide comprises a first end and a second end; and a non-polarization maintaining optical waveguide configured to connect to the core unit assembly, wherein the first end of the at least one polarization maintaining optical waveguide is connected to the core unit assembly, wherein the second end of the at least one polarization maintaining optical waveguide is configured to be connected to the laser module, wherein the core unit assembly is attached to the glass circuit board, and wherein the at least one polarization maintaining optical waveguide and the non-polarization maintaining optical waveguide are each fabricated into the glass circuit board.

13. The integrated glass waveguide assembly of claim 12, wherein the core unit assembly further comprises a first component and an electrical interconnect, wherein the first component comprises at least one of an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, or a memory chip, and wherein the electrical interconnect connects the transceiver chip to the first component.

14. The integrated glass waveguide assembly of any of claims 12 or 13, further comprising: a glass-waveguide-to-fiber connector; wherein a first end of the non-polarization maintaining optical waveguide is connected to the transceiver chip, and wherein a second end of the non-polarization maintaining optical waveguide is connected to the glass-waveguide-to-fiber connector.

15. The integrated glass waveguide assembly of any of claims 12–14, wherein the integrated glass waveguide assembly does not include any polarization maintaining optical fibers.

16. The integrated glass waveguide assembly of any of claims 12–15, wherein the integrated glass waveguide assembly does not include an electrical printed circuit board.

17. The integrated glass waveguide assembly of any of claims 12–16, wherein the integrated glass waveguide assembly does not include multiple glass waveguide interconnects.

18. The integrated glass waveguide assembly of any of claims 12–17, further comprising: a laser module.

19. The integrated glass waveguide assembly of any of claims 12–18, wherein the non- polarization maintaining optical waveguide or the at least one polarization maintaining optical waveguide comprises at least one of potassium or silver.

20. The integrated glass waveguide assembly of any of claims 12–19, wherein a first polarization maintaining optical waveguide of the at least one polarization maintaining optical waveguide includes a first segment and additional segments, wherein the first segment is connected to the laser module, wherein the first segment splits into the additional segments, and wherein each of the additional segments are connected to the core unit assembly.

21. The integrated glass waveguide assembly of any of claims 12–20, wherein the each polarization maintaining optical waveguide of the at least one polarization maintaining optical waveguide has a propagation length of between about 3 millimeters and about 500 millimeters.

22. The integrated glass waveguide assembly of any of claims 12–21, wherein the at least one polarization maintaining optical waveguide comprises a high birefringence section and a low birefringence section, wherein the high birefringence section has a higher birefringence relative to the low birefringence section.

23. The integrated glass waveguide assembly of any of claims 12–21, wherein the each polarization maintaining optical waveguide of the at least one polarization maintaining optical waveguide has a polarization extinction ratio of about 23 decibels or more with an angular misalignment of less than about three degrees.

24. The integrated glass waveguide assembly of claim 23, wherein the each polarization maintaining optical waveguide of the at least one polarization maintaining optical waveguide defines a propagation length and a beat length, wherein a length ratio value is the propagation length divided by the beat length, and wherein the ratio value is less than about 0.02 away from half of an integer.

25. A method for making an integrated glass waveguide assembly, the method comprising: fabricating a polarization maintaining optical waveguide in a glass circuit board, wherein the polarization maintaining optical waveguide comprises a first end and a second end; fabricating a non-polarization maintaining optical waveguide in the glass circuit board, wherein the non-polarization maintaining optical waveguide comprises a first end and a second end; attaching a core unit assembly to the glass circuit board, wherein the core unit assembly comprises a transceiver chip; connecting the core unit assembly to the first end of the polarization maintaining optical waveguide and to the first end of the non-polarization maintaining optical waveguide; attaching a laser module to the second end of the polarization maintaining optical waveguide; and attaching a glass-waveguide-to-fiber connector to the second end of the non-polarization maintaining optical waveguide.

26. The method of claim 25, wherein the transceiver chip of the core unit assembly is connected to the first end of the polarization maintaining optical waveguide and to the first end of the non-polarization maintaining optical waveguide, wherein the core unit assembly comprises a first component and an electrical interconnect, wherein the first component comprises an application specific integrated circuit, a switch chip, a computing chip, a data processing chip, or a memory chip, wherein the electrical interconnect connects the transceiver chip and the first component.

27. The method of claim 25 or 26, wherein fabricating the polarization maintaining optical waveguide in the glass circuit board comprises:completing an ion-exchange cycle with a first material, wherein the first material comprises at least one of silver or potassium.

28. The method of claim 27, wherein the ion-exchange cycle is performed at a first temperature, wherein fabricating the non-polarization maintaining optical waveguide in the glass core or glass circuit board comprises completing a second ion-exchange cycle with a second material at a second temperature, wherein the second ion-exchange cycle is completed after the first ion-exchange cycle, wherein the first temperature is higher than the second temperature, and wherein the first material is different than the second material.

29. The method of claim 28, wherein the first material comprises potassium, and wherein the second material comprises silver.

30. The method of any of claims 27–29, further comprising: positioning one or more masks on a surface of the glass circuit board, wherein the one or more masks leave an exposed surface area on the glass circuit board, wherein the one or more masks are positioned before completing any ion-exchange cycle.

31. The method of claim 30, further comprising: removing the one or more masks from the surface of the glass circuit board; and completing an additional ion-exchange cycle using a material comprising sodium after the one or more masks have been removed from the surface of the glass circuit board.

32. The method of any of claims 26–31, wherein the glass circuit board that is formed does not include any polarization maintaining optical fibers, any electrical printed circuit board, or multiple glass waveguide interconnects.

33. The method of any of claims 26–32, wherein the polarization maintaining optical waveguide has a polarization extinction ratio of about 23 decibels or more with an angular misalignment of less than about three degrees, wherein the polarization maintaining opticalwaveguide defines a length and a beat length, wherein a ratio value is the length divided by the beat length, and wherein the ratio value is less than about 0.02 away from half of an integer.

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