WO2023114260A1

WO2023114260A1 - Glass-based optical-to-optical coupling arrangement in high density interconnection configurations

Info

Publication number: WO2023114260A1
Application number: PCT/US2022/052783
Authority: WO
Inventors: Kalpendu Shastri; Sriram Tyagarajan; Ravinder Kachru; David Snyder; Steven E. Strauss; Rao Yelamarty
Original assignee: Aayuna Inc.
Priority date: 2021-12-14
Filing date: 2022-12-14
Publication date: 2023-06-22

Abstract

A glass-based coupling component including a set of waveguides formed in a particular pattern is used to provide interconnection between selected elements within a high density optical-electrical interconnection assembly (for example, between a set of photonic integrated circuits and an external faceplate connector). A separate interface element (including an array of fiber stubs) is used to couple each photonic integrated circuit to the glass-based coupling component. A pair of V-groove support members are included in each interface element and used to support the array of fiber stubs in alignment with both a set of waveguides formed in the glass-based coupling component and a set of optical signals exiting the photonic integrated circuits.

Description

GLASS-BASED OPTICAL-TO-OPTICAL COUPLING ARRANGEMENT IN HIGH DENSITY INTERCONNECTION CONFIGURATIONS

Cross-Reference to Related Applications

This application claims the benefit of US Provisional Application No . 63/289 , 417 filed December 14 , 2021 , and incorporated herein by reference .

Background, of the Invention

High density optical/electrical ( O/E ) interconnection arrangements typically employ a set of photonic integrated circuits and related electrical signal routing/ switching AS ICs disposed on a single substrate ( such as a printed circuit board - PCB ) . Some arrangements also include one or more laser sources also mounted on the PCB .

FIG . 1 illustrates one exemplary arrangement from US Patent 10 , 725 , 254 issued to Applicant on July 28 , 2020 , which illustrates a set of optical/electrical ( OE ) circuits 1 disposed around a routing/ switching AS IC 2 , all of these components mounted on a PCB 3 . A set of laser sources 4 ( also referred to as laser engines ) is shown as also mounted on PCB 3 .

To date , the optical interconnections between various ones of these elements have used arrays of optical fibers , which necessitates providing optical alignment between the core regions of the fibers and the optical waveguides on the photonic integrated circuits ( PICs ) / lasers . Arrays of polari zation-maintaining fibers 5 are shown as interconnecting laser engines 4 and OEs 1 , with additional fiber arrays 6 are coupled to OEs 1 and are ultimately "collected" to exit PCB 3 along a backplane/ faceplate coupling 7 to external optical components . While passive alignment configurations have been developed, increasing the optical signal path density in such interconnection configurations requires the management of a large number of optical fibers which may become unwieldly very quickly .

Summary of the Invention

The need remaining in the art is addressed by the present invention, which relates to replacing the fiber arrays used as internal connections in 0/E systems with a glass-based optical-to- optical coupling component .

In accordance with the principles of the present invention, a glass-based coupling component is formed to include a set of waveguides formed in a particular pattern that will provide interconnection between selected elements , such as , for example , between a set of photonic integrated circuits and an external faceplate connector . In this example , a separate interface element ( including an array of fiber stubs ) is used to couple each photonic integrated circuit to the glass-based coupling component . A pair of V-groove support members are included in each interface element and used to support the array of fiber stubs in alignment with both a set of waveguides formed in the glass-based coupling component and a set of optical signals exiting the photonic integrated circuits .

An exemplary embodiment may take the form of an arrangement for providing optical-to-optical connections associated with photonic integrated circuits , comprising a glass-based coupling component including a plurality of optical waveguides formed therein, the plurality of optical waveguides disposed a defined pattern and a plurality of fiber interface elements disposed around a periphery of the glass-based interface coupling component . Each fiber interface element includes an array of fiber stubs , a first fiber support disposed underneath a first end termination of the array of fiber stubs , and a second fiber support disposed underneath a second, opposing end termination of the array of fiber stubs . Each fiber interface element is configured such that its first end termination of the array of fiber stubs is disposed in optical alignment with a set of optical waveguides from the plurality of optical waveguides formed in the glass-based interface component , and its second end termination of the array of fiber stubs is disposed in optical alignment with a set of optical signals exiting a photonic integrated circuit .

Other and further features and embodiments will become apparent during the course of the following discussion and by reference to the accompanying drawings .

Brief Description of the Drawings

Referring now to the drawings , where like numerals represent like parts in several views :

FIG . 1 illustrates one exemplary high density optical/electrical ( 0/E ) interconnection arrangement as found in the prior art , using fiber arrays to provide the optical interconnections ;

FIG . 2 illustrates a glass-based optical-to-optical coupling component formed in accordance with the principles of the present invention to be used as the coupling component in a high density O/E interconnection arrangement ;

FIG . 3 is a side view of an exemplary embodiment of a fiber interface element used to provide optical coupling between a photonic integrated circuit and the glass-based coupling component in the configuration as shown in FIG . 2 ;

FIG . 4 is a top view of the arrangement of the fiber interface element shown in FIG . 3 ;

FIG . 5 is a close-up view of a portion of a fiber interface element , showing a region where a fiber support is positioned next to a photonic integrated circuit ;

FIG . 6 illustrates an alternative embodiment of the fiber interface element ; FIG . 7 illustrates another embodiment of the present invention, in this case where the combination of a fiber interface element and a glass-based coupling component is used to provide chip-to-chip coupling within an O/E assembly itsel f ;

FIG . 8 depicts yet another embodiment of the present invention, utili zing a first glass-based coupling component to provide connections between photonic integrated circuits and an external faceplate , and a second glass-based coupling component to provide optical interconnections between photonic integrated circuits forming an O/E assembly;

FIG . 9 illustrates an arrangement of the present invention that is used to provide optical coupling between laser engines included in high density optical-electrical interconnection assembly photonic integrated circuits contained within the assembly;

FIG . 10 includes an alternative configuration to the arrangement shown in FIG . 9 , where the waveguides formed within glass substrates are used in a configuration where the laser engines are inverted with respect to the orientation of the O/E assembly; and

FIG . 11 shows a glass-based coupling component formed in accordance with the present invention that may be used within an opto-electronic architecture where the AS IC component is separately formed and positioned on a common substrate with a completely formed opto-electric subassembly .

Description of the Invention

As will be described in detail below, the present invention is directed to replacing the fiber arrays used as internal connections in O/E systems with a glass-based optical-to-optical coupling component . Reference is made to FIG . 2 , which illustrates a glassbased coupling component 10 formed in accordance with the principles of the present invention . Glass-based coupling component 10 is shown surrounding an exemplary high density optical-electrical interconnection assembly 12 . Assembly 12 is shown as comprising a plurality of silicon-based photonic integrated circuits 14 surrounding a routing/ switching electronic AS IC 16 . As described above in association with FIG . 1 , these components are all mounted on a PCB 18 , which is used to provide electrical connection between AS IC 16 and photonic integrated circuits 14 .

In accordance with the present invention, the use of fiber arrays as the optical output signal paths from photonic integrated circuits to an associated connector ( such as fiber arrays 6 shown in FIG . 1 ) is replaced by glass-based coupling component 10 and a plurality of relatively short fiber interface elements 20 that provide optical coupling between photonic integrated circuits 14 and optical waveguides formed on glass-based optical coupling component 10 . As shown, optical waveguides 22 are formed in defined locations within glass-based coupling component 10 so as to provide the complete set of optical paths required to interconnect high density OE interconnection assembly 12 with an optical assembly faceplate 40 .

FIG . 3 is a side view of an exemplary embodiment of fiber interface element 20 as used to provide optical coupling between a photonic integrated circuit 14 and glass-based coupling component 10 , with FIG . 4 illustrating a top view of the same interface element 20 . With reference to both FIGs . 3 and 4 , fiber interface element 20 is shown as comprising a plurality of short fiber stubs 24 (best illustrated in FIG . 4 ) that span the gap between a first fiber support 26 and a second fiber support 28 . As shown in FIG . 3 , first fiber support 26 is positioned adj acent to photonic integrated circuit 14 , and is formed to include a plurality of V- grooves 30 to support a first end portion 24- 1 of fiber stubs 24 in a defined spacing (pitch) and at a height such that the core regions of fiber stubs 24 will be in optical alignment with the optical signal paths 0 exiting photonic integrated circuit 14 . A set of alignment fiducials 32 may be formed on first fiber support 26 and photonic integrated circuit 14 to provide the optical alignment . FIG . 5 is a close-up view of the region where first fiber support 26 is positioned next to photonic integrated circuit 14 . The plurality of V-grooves 30 as formed in first fiber support 26 is clearly shown in this view, as well as the optical signal paths 0 exiting photonic integrated circuit 14 .

In a similar fashion, second fiber support 28 is formed to include a plurality of V-grooves 34 that are particularly configured to provide alignment between a second end portion 24-2 of fiber stubs 24 and optical waveguides 22 formed in glass-based coupling component 10 . FIG . 6 illustrates an alternative embodiment of the fiber interface element ( referred to here as element 20a ) . In this case , instead of using second fiber support 28 as shown in FIGs . 3 and 4 , an edge region of the glass material forming coupling component 10 is processed to form a ledge 10L that may support second end portions 24-2 of fiber stubs 24 .

While shown in the above figures as providing optical coupling between photonic circuits 14 and a faceplate termination 40 of the assembly, the combination of fiber interface element 20 and glass-based coupling component 10 may also be used to provide chip-to-chip coupling within an O/E assembly itsel f , as shown in FIG . 7 . Similar to the arrangement described above , a fiber interface element 20 is used to provide optical coupling between photonic integrated circuit 14 and glass-based coupling component 10 . However, in this case , coupling component 10 is formed to include glass-based waveguides 22 that provide optical signal paths between one photonic integrated circuit and another .

In the example illustrated in FIG . 7 , a set of photonic integrated circuits 14 . 1 - 14 . 7 are disposed in the arrangement each, each having its own fiber interface element 20 . i ( i=l— 7 ) for providing optical coupling to waveguides 22 within glass-based coupling component 10 . Thus , optical signals at a first chip ( such as photonic integrated circuit 14 . 1 ) may be coupled to a second chip ( such as photonic integrated circuit 14 . 3 ) via a particular waveguide 22A formed within glass-base coupling component 10 . Advantageously, the glass material of component 10 may be processed in a relatively straightforward manner to create a speci fic waveguide pattern 22-P useful for a particular interconnection of photonic circuits 14 . I f another interconnection arrangement is required for a di f ferent application, another glass component 10 is process to create the di f ferent pattern .

It is to be understood that yet another embodiment of the present invention may utili ze a combination of first glass-based coupling component between the photonic integrated circuits and external elements (via a faceplate ) , as well as a second glassbased coupling component to provide optical signal paths within the O/E assembly from one photonic integrated circuit to another . FIG . 8 illustrates one such arrangement , utili zing a first glass-based coupling component 10- 1 to provide connections between photonic integrated circuits 14 and faceplate 40 , and a second glass-based coupling component 10-2 to provide optical interconnections between selected ones of the photonic integrated circuits 14 . Routing/ switching electronic AS IC 16 is depicted as positioned underneath second coupling component 10-2 .

A similar glass-based coupling arrangement may be used to provide optical coupling between laser engines included in high density optical-electrical interconnection assembly 12 and associated photonic integrated circuits 14 , as shown in FIG . 9 . Here , a first glass-based coupling component 10A is shown as including a plurality of waveguides 22A that are coupled between a first fiber interface element 20A and an external faceplate 40 . A first laser engine 90A is shown as disposed on first coupling component 10A, where laser engine 90A provides one or more free- space output CW beams 92 for using by selected photonic integrated circuits 14. In order to maintain the integrity of the optical beams, a separate set polarization-maintaining fiber stubs 24-PM, also supported in this case by first fiber interface element 20A. Further illustrated in FIG. 9 is the case where a laser engine 90B is disposed on a second glass-based coupling component 10B in a position where output beams 92 are directly coupled into photonic integrated circuit 14. As shown, second glass-based coupling component 10B also includes a plurality of waveguides 22B for connecting a second fiber interface element 20B with external faceplate 40.

Additionally, waveguides formed within glass substrates may be used in an inverted configuration, as shown in FIG. 10, for attaching laser engines to an opto-electronic assembly. In this illustration, a pair of laser engines 90.1 and 90.2 is shown as coupled to glass-based coupling components 10.1, 10.2 (which may either be formed as individual glass members or a single glassbased substrate for coupling all laser engines to the optoelectronic assembly) . Individual photonic integrated circuits 14.1, 14.2 are shown as coupled to glass-based coupling components 10.1 and 10.2, respectively. Since the use of polarizationmaintaining waveguides are preferred for coupling out of the laser sources, polarization-maintaining fiber stubs 24-PM are used within fiber interface elements 20.1 and 20.2, and the waveguides formed in the glass substrates are formed to maintain a TE polarization.

In another embodiment, a glass-based coupling component 10 may be used within an opto-electronic architecture where the ASIC component is separately formed and positioned on a common substrate with a completely formed opto-electric subassembly. This is shown in FIG. 11. Such an arrangement allows for a designer to purchase a fully-formed opto-electronic subassembly 80, including a socket connection 82. A separate ASIC 180 formed for a particular application may be coupled to subassembly 80 by the designer by interconnecting these elements on a host PCB 182 . Again, a glassbased optical coupling component 10 may be included within subassembly 80 to minimi ze the number of physical fibers that need to be housed within the structure . While the principles of the present invention have been particularly shown and described with respect to illustrative and preferred embodiments , it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention, which should be limited only by the scope of the claims appended hereto .

Claims

What is claimed is :

1 . An arrangement for providing optical-to-optical connections associated with photonic integrated circuits , comprising : a glass-based coupling component including a plurality of optical waveguides formed therein, the plurality of optical waveguides disposed a defined pattern; and a plurality of fiber interface elements disposed around a periphery of the glass-based interface coupling component , each fiber interface element including an array of fiber stubs ; a first fiber support disposed underneath a first end termination of the array of fiber stubs ; and a second fiber support disposed underneath a second, opposing end termination of the array of fiber stubs , wherein each fiber interface element is configured such that its first end termination of the array of fiber stubs is disposed in optical alignment with a set of optical waveguides from the plurality of optical waveguides formed in the glass-based interface component , and its second end termination of the array of fiber stubs is disposed in optical alignment with a set of optical signals exiting a photonic integrated circuit .

2 . The arrangement as defined in claim 1 wherein the first and second fiber supports of each fiber interface element include a set of V-grooves for supporting the array of fiber stubs in optical alignment with the glass-based optical coupling component and the photonic integrated circuit .

3. The arrangement as defined in claim 1 wherein the first and second fiber supports of selected ones of the plurality of fiber interface elements further comprise alignment fiducials for mating with like fiducials formed on both the glass-based interface coupling component and the photonic integrated circuit .

4 . The arrangement as defined in claim 1 , wherein the glassbased coupling component is disposed to surround a plurality of individual photonic integrated circuits , with a separate fiber interface element used to couple each individual photonic integrated circuit to a set of waveguides formed in the glass-based coupling component .

5 . The arrangement as defined in claim 4 , wherein the defined pattern of optical waveguides formed in the glass-based coupling component are arranged to terminate along a common edge of the glass-based coupling component regardless of the orientation of the surrounded plurality of photonic integrated circuits .

6. The arrangement as defined in claim 5 wherein waveguide terminations along the common edge are thereafter coupled to a common faceplate component .

7 . The arrangement as defined in claim 1 , wherein the glassbased coupling component is surrounded by a set of individual photonic integrated circuits , with a separate fiber interface element used to couple each individual photonic integrated circuit to a set of waveguides formed in the glass-based coupling component .

8 . The arrangement as defined in claim 7 , wherein the defined pattern of optical waveguides formed in the glass-based coupling component are disposed to provide a set of defined optical signal paths between selected pairs of photonic integrated circuits .

9 . The arrangement as defined in claim 1 , wherein the glassbased coupling component comprises a first glass-based coupling component disposed to surround a plurality of individual photonic integrated circuits , with a separate , first fiber interface element used to couple each individual photonic integrated circuit to a set of first waveguides formed in the first glass-based coupling component ; and a second glass-based coupling component disposed to be surrounded by the plurality of individual photonic integrated circuits , with a separate , second fiber interface element used to couple individual photonic integrated circuits to the second glassbased coupling component , wherein a set of second waveguides formed in the second glass-based coupling component are disposed in a pattern defined to form optical signal paths between separate ones of the photonic integrated circuits .