# US 2023/0055077 A1 · Optical hybrid-waveguide electro-optical modulator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2023/0055077 A1 - Document ID: US20230055077A1 - Status: Published application - Kind: A1 - Application number: 17/820,673 - Filed: 2022-08-18 - Published: 2023-02-23 - Earliest claimed: 2021-08-19 - Assignees: Nokia Solutions and Networks Oy - Applicants: Nokia Solutions and Networks Oy - Inventors: Ruizhi SHI; Ari NOVACK; Alexander RYLYAKOV; Eu-Jin Andy LIM - Web page: https://patentgrep.com/patent/US20230055077A1 ## CPC - G02F 1/035: in an optical waveguide structure - G02B 6/12004: {Combinations of two or more optical elements} - G02F 1/0151: {modulating the refractive index} - G02F 1/212: {Mach-Zehnder type} - G02F 1/225: in an optical waveguide structure - G02B 2006/12061: {Silicon} - G02B 2006/12097: {Ridge, rib or the like} - G02B 2006/12142: {Modulator} - G02F 2201/126: push-pull - G02F 2201/127: travelling wave - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An apparatus includes a lithium niobate (LN) layer, and a planar electro-optical modulator having at least one hybrid optical core segment formed of a portion of the LN layer and an optical guiding rib. The optical guiding rib may be located in a top silicon layer of a silicon photonics (SiP) chip, to which a thin-film LN chip is flip-chip mounted, and may be coupled to optical waveguide cores in a first silicon core layer of the SiP chip. One or more drive electrodes are disposed between a substrate of the SiP chip and the LN layer. In some embodiments hybrid optical core segments may include silicon nitride core segments and may form an MZM configured to be differentially or dual-differentially driven. ## Claims ### Claim 1 An apparatus, comprising: a silicon substrate; a lithium niobate (LN) layer; a planar electro-optic Mach-Zehnder modulator extending along a main surface of the silicon substrate and comprising two optical waveguide arms connected to receive light in parallel from an optical splitter, and at least two traveling wave (TW) drive electrodes; an electrical driver connected to provide at least one drive signal to the at least two TW drive electrodes such that the two optical waveguide arms are driven in a push-pull manner, the electrical driver having differential outputs connected to the at least two TW drive electrodes; and wherein each of the two optical waveguide arms comprises a hybrid optical core segment located adjacent at least a corresponding one of the at least two TW drive electrodes, each of the hybrid optical waveguide core segments comprising a portion of the LN layer and an optical guiding rib located adjacent to and along the portion of the LN layer, each optical guiding rib being integral with the silicon substrate and comprising silicon therein. ### Claim 2 (depends on 1) The apparatus of claim 1, further comprising two additional TW drive electrodes, the at least two TW drive electrodes and the two additional TW drive electrodes forming two pairs of TW drive electrodes, each of the pairs of TW drive electrodes being disposed to electro-optically modulate light in a corresponding one of the two optical waveguide arms. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the at least two TW drive electrodes comprise two pairs of TW drive electrodes, each pair disposed to modulate light in a respective one of the two optical waveguide arms, wherein the electrical driver has two pairs of differential outputs, each pair of differential outputs being electrically connected to a corresponding one of the pairs of TW drive electrodes. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the LN layer extends over the at least two TW electrodes. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein each optical guiding rib is a silicon rib. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein each optical guiding rib is a silicon nitride rib. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the at least two TW drive electrodes are between the LN layer and the substrate. ### Claim 8 (depends on 1) The apparatus of claim 1, further comprising one or more planar optical waveguides extending along the main surface of the silicon substrate at a different distance therefrom than the ribs, further comprising at least one vertical coupler for optically coupling the one or more planar optical waveguides and the ribs. ### Claim 9 (depends on 1) The apparatus of claim 1, further comprising one or more optical devices disposed in a layer between the silicon substrate and the ribs. ### Claim 10 (depends on 3) The apparatus of claim 3, further comprising one or more optical devices disposed in a layer between the silicon substrate and the ribs. ### Claim 11 (depends on 7) The apparatus of claim 7, further comprising a plurality of vertically stacked silicon layers disposed between the silicon substrate and the LN layer. ### Claim 12 (depends on 1) The apparatus of claim 1, further comprising a silicon nitride layer disposed between two silicon layers. ### Claim 13 (depends on 2) The apparatus of claim 2 wherein the electrical driver has two pairs of differential outputs, each pair of differential outputs being electrically connected to a corresponding one of the pairs of TW drive electrodes. ### Claim 14 (depends on 3) The apparatus of claim 3, wherein the LN layer extends over the at least two TW electrodes. ### Claim 15 (depends on 2) The apparatus of claim 2, further comprising one or more optical devices disposed in a layer between the silicon substrate and the ribs. ### Claim 16 (depends on 2) The apparatus of claim 2 comprising a silicon layer disposed between the silicon substrate and the at least two TW drive electrodes. ### Claim 17 (depends on 13) The apparatus of claim 13 comprising a silicon layer disposed between the silicon substrate and the at least two TW drive electrodes.