# US 2019/0320249 A1 · Planar photonic switch fabrics with reduced waveguide crossings > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0320249 A1 - Document ID: US20190320249A1 - Status: Published application - Kind: A1 - Application number: 16/453,257 - Filed: 2019-06-26 - Published: 2019-10-17 - Earliest claimed: 2017-12-12 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Nicolas Dupuis; Benjamin Lee - Web page: https://patentgrep.com/patent/US20190320249A1 ## CPC - H04Q 11/0005: {Switch and router aspects} - G02B 6/356: {in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links (switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001)} - G02B 6/3596: {With planar waveguide arrangement, i.e. in a substrate, regardless if actuating mechanism is outside the substrate} - H04Q 2011/0022: {using fibre gratings} - H04Q 2011/0058: {Crossbar; Matrix} - H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract Techniques for using planar photonic switch fabrics with reduced waveguide crossings are described. In one embodiment, a system is provided that comprises a memory that stores computer-executable components and a processor that executes computer-executable components stored in the memory. In one implementation, the computer-executable components comprise an arrangement component that arranges a first planar switch fabric topology. The computer-executable components further comprise a transformation component that interleaves a plurality of inputs of the first planar switch fabric topology and a plurality of outputs of the first planar switch fabric topology to form a second planar switch fabric topology, the second planar switch fabric topology having a lower number of waveguide crossings than the first planar switch fabric topology. ## Claims ### Claim 1 A system, comprising: a memory that stores computer executable components; and a processor that executes the computer executable components stored in the memory, wherein the computer executable components comprise: an arrangement component that arranges a first planar switch fabric topology topology with a defined amount of waveguides between a plurality of inputs of the first planar switch fabric topology and a plurality of outputs of the first planar switch fabric topology; and a waveguide routing component that routes a first waveguide of the first planar switch fabric topology around a perimeter of a first input/output (I/O) stage of the first planar switch fabric topology to produce a second planar switch fabric topology, the first I/O stage being located on an interior of the second planar switch fabric topology, the second planar switch fabric topology having a lower number of waveguide crossings of the waveguides than the first planar switch fabric topology, wherein the second planar switch fabric topology has the defined amount of waveguides. ### Claim 2 (depends on 1) The system of claim 1, wherein the first I/O stage comprises an input stage or an output stage. ### Claim 3 (depends on 1) The system of claim 1, wherein a signal, an input or a light wave is injected into the first I/O stage of the second planar switch fabric topology using a second waveguide located on a separate planar layer as the first waveguide. ### Claim 4 (depends on 3) The system of claim 3, wherein a first layer of the second planar switch fabric topology is fabricated in a first material, and a second layer of the second planar switch fabric topology is fabricated in a second material that is different from the first material. ### Claim 5 (depends on 4) The system of claim 4, wherein the second layer of the second planar switch fabric topology comprises a second waveguide that is fabricated in silicon nitride. ### Claim 6 (depends on 1) The system of claim 1, wherein a signal, input, or light wave is injected into the first I/O stage of the second planar switch fabric topology using an out of plane coupling structure. ### Claim 7 (depends on 6) The system of claim 6, wherein the out of plane coupling structure comprises a grating coupler. ### Claim 8 A computer-implemented method, comprising: arranging, by a system operatively coupled to a processor, a first planar switch fabric topology with a defined amount of waveguides between a plurality of inputs of the first planar switch fabric topology and a plurality of outputs of the first planar switch fabric topology; and routing, by the system, a first waveguide of the first planar switch fabric topology around a perimeter of a first input/output (I/O) stage of the first planar switch fabric topology to produce a second planar switch fabric topology, the first I/O stage being located on an interior of the second planar switch fabric topology, the second planar switch fabric topology having a lower number of waveguide crossings of the waveguides than the first planar switch fabric topology, wherein the second planar switch fabric topology has the defined amount of waveguides. ### Claim 9 (depends on 8) The computer-implemented method of claim 8, wherein the first I/O stage comprises an input stage or an output stage. ### Claim 10 (depends on 8) The computer-implemented method of claim 8, further comprising: injecting, by the system, a signal, an input or a light wave into the first I/O stage of the second planar switch fabric topology using an out of plane coupling structure. ### Claim 11 (depends on 10) The computer-implemented method of claim 10, further comprising: injecting, by the system, a signal, an input or a light wave into the first I/O stage of a back side of the second planar switch fabric topology. ### Claim 12 (depends on 10) The computer-implemented method of claim 10, wherein the out of plane coupling structure comprises an angled reflective surface. ### Claim 13 (depends on 8) The computer-implemented method of claim 8, further comprising: injecting, by the system, a signal, an input or a light wave into the first I/O stage of the second planar switch fabric topology using a layer of planar optical waveguides. ### Claim 14 (depends on 8) The computer-implemented method of claim 8, wherein the second planar switch fabric topology comprises a data transmitting optical emitter that is integrated within an interior of the second planar switch fabric topology. ### Claim 15 A computer program product that facilitates implementation of planar photonic switch fabrics with reduced waveguide crossings, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions being executable by a processor to cause the processor to: arrange a first planar switch fabric topology with a defined amount of waveguides between a plurality of inputs of the first planar switch fabric topology and a plurality of outputs of the first planar switch fabric topology; and route a first waveguide of the first planar switch fabric topology around a perimeter of a first input/output (I/O) stage of the first planar switch fabric topology to produce a second planar switch fabric topology, the first I/O stage being located on an interior of the second planar switch fabric topology, the second planar switch fabric topology having a lower number of waveguide crossings of the waveguides than the first planar switch fabric topology, wherein the second planar switch fabric topology has the defined amount of waveguides. ### Claim 16 (depends on 15) The computer program product of claim 15, wherein the first I/O stage comprises an input stage or an output stage. ### Claim 17 (depends on 15) The computer program product of claim 15, wherein the second planar switch fabric topology comprises a data receiving optical detector that is integrated within an interior of the second planar switch fabric topology. ### Claim 18 (depends on 15) The computer program product of claim 15, wherein a signal, an input or a light wave is injected into the first I/O stage of the second planar switch fabric topology using an out of plane coupling structure. ### Claim 19 (depends on 18) The computer program product of claim 18, wherein the out of plane coupling structure comprises a grating coupler. ### Claim 20 (depends on 15) The computer program product of claim 15, wherein a signal, an input or a light wave is injected into the first I/O stage of a top side of the second planar switch fabric topology.