# US 2025/0093567 A1 · Waveguide Display Having Gratings with Continuous Phase Shifting > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0093567 A1 - Document ID: US20250093567A1 - Status: Published application - Kind: A1 - Application number: 18/805,955 - Filed: 2024-08-15 - Published: 2025-03-20 - Earliest claimed: 2023-09-15 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Brandon Born; Wencong Zhu; Jong Young Hong; Se Baek Oh - Web page: https://patentgrep.com/patent/US20250093567A1 ## CPC - G02B 6/0016: {Grooves, prisms, gratings, scattering particles or rough surfaces} - G02B 6/34: utilising prism or grating {(G02B6/293 takes precedence)} - G02B 6/0036: {2-D arrangement of prisms, protrusions, indentations or roughened surfaces} - G02B 6/124: Geodesic lenses or integrated gratings - G02B 27/0172: {characterised by optical features} - G02B 2027/0174: {holographic} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A display may include a waveguide that directs image light to an eye box. The waveguide may include an optical coupler that redirects and replicates the light. The coupler may include a surface relief grating (SRG). The SRG may have a pitch that varies continuously along an axis orthogonal its ridges. The pitch may vary sinusoidally, linearly, parabolically, or according to other continuous and differentiable functions of position along the axis. The SRG may diffract the light. Upon diffracting the light, the SRG may impart a phase to the light. The phase may vary continuously as a function of position along a first axis and may, if desired, vary continuously as a function of position along a second axis orthogonal to the first axis. The SRG may prevent formation of coherent light paths after replication, thereby maximizing the efficiency of the system. ## Claims ### Claim 1 An electronic device comprising: a waveguide configured to propagate light; and an optical coupler configured to redirect and replicate the light, wherein the optical coupler includes a substrate on the waveguide, and a surface relief grating (SRG) in the substrate, wherein the SRG has ridges with a pitch that varies continuously as a function of position along an axis orthogonal to the ridges. ### Claim 2 (depends on 1) The electronic device of claim 1, wherein the pitch varies periodically as a function of position along the axis. ### Claim 3 (depends on 2) The electronic device of claim 2, wherein the pitch varies sinusoidally as a function of position along the axis. ### Claim 4 (depends on 3) The electronic device of claim 3, wherein the ridges follow periodic paths. ### Claim 5 (depends on 4) The electronic device of claim 4, wherein the periodic paths comprise sinusoidal paths. ### Claim 6 (depends on 1) The electronic device of claim 1, wherein the pitch varies parabolically as a function of position along the axis. ### Claim 7 (depends on 6) The electronic device of claim 6, wherein the SRG has a length along the axis and the SRG has a minimum pitch halfway along the length. ### Claim 8 (depends on 6) The electronic device of claim 6, wherein the SRG has a length along the axis and the SRG has a minimum pitch that is offset from halfway along the length. ### Claim 9 (depends on 1) The electronic device of claim 1, further comprising: an additional SRG in the substrate and overlapping the SRG, wherein the additional SRG has additional ridges oriented non-parallel with respect to the ridges in the SRG, and wherein the additional ridges have an additional pitch that varies continuously as a function of position along an additional axis orthogonal to the additional ridges. ### Claim 10 (depends on 1) The electronic device of claim 1, wherein the waveguide has a first lateral surface, a second lateral surface opposite the first lateral surface, and the substrate is layered on the first lateral surface, the electronic device further comprising: an additional substrate layered on the second lateral surface; and an additional SRG in the additional substrate and overlapping the SRG, wherein the additional SRG has additional ridges oriented non-parallel with respect to the ridges in the SRG, and wherein the additional ridges have an additional pitch that varies continuously as a function of position along an additional axis orthogonal to the additional ridges. ### Claim 11 (depends on 1) The electronic device of claim 1, further comprising: an input coupler configured to couple the light into the waveguide; and an output coupler configured to couple the light out of the waveguide, the optical coupler comprising a cross-coupler configured to redirect the light from the input coupler towards the output coupler. ### Claim 12 An electronic device comprising: a waveguide configured to propagate light; and an optical coupler configured to redirect and replicate the light, wherein the optical coupler includes a substrate on the waveguide, and a diffractive grating in the substrate, wherein the diffractive grating is configured to impart a phase to the light upon diffracting the light and wherein the phase varies continuously as a function of position along an axis. ### Claim 13 (depends on 12) The electronic device of claim 12, wherein the function is a continuous and differentiable function. ### Claim 14 (depends on 13) The electronic device of claim 13, wherein the continuous and differentiable function is a sinusoidal function. ### Claim 15 (depends on 13) The electronic device of claim 13, wherein the continuous and differentiable function is a parabolic function. ### Claim 16 (depends on 12) The electronic device of claim 12, wherein the continuous and differentiable function is a linear function. ### Claim 17 (depends on 12) The electronic device of claim 12, wherein the phase varies continuously as a function of position along an additional axis orthogonal to the axis. ### Claim 18 (depends on 17) The electronic device of claim 17, wherein the phase varies parabolically along the axis and varies parabolically along the additional axis. ### Claim 19 (depends on 12) The electronic device of claim 12, wherein the diffractive grating comprises a surface relief grating. ### Claim 20 An electronic device comprising: a waveguide configured to propagate light; and an optical coupler configured to redirect and replicate the light, wherein the optical coupler includes a substrate on the waveguide, and a surface relief grating (SRG) in the substrate, wherein the SRG has ridges and troughs that follow sinusoidal paths.