WO2019136166A1 - Métasurfaces dépendant de l'angle ou dépendant de la polarisation avec grand champ de vision - Google Patents

Métasurfaces dépendant de l'angle ou dépendant de la polarisation avec grand champ de vision Download PDF

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Publication number
WO2019136166A1
WO2019136166A1 PCT/US2019/012205 US2019012205W WO2019136166A1 WO 2019136166 A1 WO2019136166 A1 WO 2019136166A1 US 2019012205 W US2019012205 W US 2019012205W WO 2019136166 A1 WO2019136166 A1 WO 2019136166A1
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angle
nanoscale elements
light
optical device
grating
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PCT/US2019/012205
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English (en)
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Wei Ting Chen
Zhujun Shi
Federico Capasso
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President And Fellows Of Harvard College
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Publication of WO2019136166A1 publication Critical patent/WO2019136166A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1809—Diffraction gratings with pitch less than or comparable to the wavelength
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G02B27/1066—Beam splitting or combining systems for enhancing image performance, like resolution, pixel numbers, dual magnifications or dynamic range, by tiling, slicing or overlapping fields of view
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G02B27/1086—Beam splitting or combining systems operating by diffraction only
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4261—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive element with major polarization dependent properties
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1866—Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials
    • G02B5/1871—Transmissive phase gratings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/0123—Head-up displays characterised by optical features comprising devices increasing the field of view

Definitions

  • FOV field of view
  • FOV field of view
  • multiple lenses with entrance/exits apertures can be combined together to be cascaded along an optical axis.
  • Such an attempt can increase design complexity, cost and device volume.
  • the FOVs can be increased by using high refractive index substrates.
  • metasurfaces composed of sub-wavelength spaced structures, have been shown to be capable of manipulating light using different parameters such as wavelength and polarization.
  • the phase libraries of the metasurface constituent structures By specifying the phase libraries of the metasurface constituent structures, the structures respond differently based on the polarization state or wavelength of the incident beam.
  • angle-dependent metasurface the engineering of a metasurface with a phase profile that varies as a function of the angle of incidence (referred to as angle-dependent metasurface hereinafter) has proved challenging and so far, has been limited to the infrared region.
  • At least one aspect of the present disclosure relates to a transmissive angle-dependent metasurface that works for light in, e.g., the visible spectrum.
  • a metasurface with tailored angle-dependent properties compact lenses and augmented reality devices with increased FOVs can be achieved.
  • phase spectra of nanopillars are designed as a function of the angle of incidence in the visible spectrum.
  • the nanopillars are assembled to form a metasurface capable of deflecting light to designed angles depending on the angles of the incident beam.
  • Such a metasurface can increase the FOV up to at least 3-fold compared to comparative devices with the same or similar specifications.
  • At least one aspect of the present disclosure relates to a waveguide display design based on polarization-dependent metagratings (also referred to as metasurface gratings).
  • the FOV may be increased by, e.g., about 70%, compared to designs based on comparative diffractive gratings.
  • Metagratings that selectively diffract out TE or TM polarized light may be provided for by the present disclosure. High polarization selectivity can thus be achieved, with minimal crosstalk between the two channels.
  • the multiplexing information in the disclosed polarization domain can be used to achieve large FOV in, e.g., AR devices.
  • One aspect of the present disclosure relates to an optical device including a metasurface grating includes a plurality of nanoscale elements, wherein the nanoscale elements define an angle-dependent phase profile that imparts a wavevector that varies depending on an angle of incidence of light.
  • the nanoscale elements include at least one of titanium dioxide, silicon nitride, a polymer, an oxide, a nitride, a sulfide, a pure element, and a combination thereof.
  • the light of incidence has a wavelength in a visible or near-infrared region of an electromagnetic spectrum.
  • a cross-section of each of the plurality of nanoscale elements has a two-fold symmetry to impart wavevectors to various polarization states of incidence.
  • a cross-section of each of the plurality of nanoscale elements has radial symmetry rendering a functionality of the device insensitive to the polarization of light.
  • the nanoscale elements define the angle-dependent phase profile such that the wavevector is a function of the angle of incidence.
  • the optical device further includes a transmissive substrate including glass or polymer, the nanoscale elements disposed on the transmissive substrate.
  • the optical device further includes a transmissive substrate with curved or flexible surfaces.
  • the metasurface grating provides an FOV that depends on the wavevector.
  • the angle-dependent phase profile is asymmetric with respective to the angle of incidence.
  • the metasurface grating provides an FOV that depends on the spatial gradient of the angle-dependent phase profile defined by the nanoscale elements.
  • the nanoscale elements comprise slanted nanopillars with a nonzero slant angle with respect to the surface normal of the metasurface grating.
  • the slanted nanopillars are arranged to introduce a Bragg resonance.
  • the angle-dependent phase profile defined by the nanoscale elements imparts an angular dispersion of light phase change that depends on a filling factor of the metasurface grating, or wherein the angle-dependent phase profile defined by the nanoscale elements imparts an angular dispersion of light transmission that depends on the filling factor of the metasurface grating.
  • an augmented reality device that includes a waveguide for overlaying augmented reality information on a view of a real-world environment, and a metasurface grating including a plurality of nanoscale elements disposed on the waveguide, wherein the nanoscale elements define an angle-dependent phase profile that imparts a wavevector that varies depending on an angle of incidence.
  • the nanoscale elements define the angle-dependent phase profile such that the wavevector is a function of the angle of incidence.
  • the metasurface grating provides an FOV that depends on the wavevector.
  • the metasurface grating provides an FOV that depends a spatial gradient of the angle-dependent phase profile defined by the nanoscale elements.
  • the nanoscale elements are slanted nanopillars with a nonzero slanted angle with respect to a surface normal of the metasurface grating, and the slanted nanopillars are arranged to introduce a Bragg resonance.
  • an omni-angle optical device includes an optical resonator or an optical filter configured to perform an optical functionality, and a metasurface grating including a plurality of nanoscale elements disposed on the optical resonator or the optical filter, wherein the nanoscale elements define an angle- dependent phase profile that imparts a wavevector that varies depending on an angle of incidence, and the angle-dependent phase profile renders the optical functionality of the optical resonator or the optical filter insensitive to the angle of incidence.
  • an optical device includes a first metasurface grating including a plurality of first nanoscale elements, wherein the first nanoscale elements define a first polarization-dependent phase profile that transmits a first light of a first polarization state in a first direction, and a second metasurface grating including a plurality of second nanoscale elements, wherein the second nanoscale elements define a second polarization-dependent phase profile that transmits a second light of a second polarization state into a second direction different from the first direction.
  • the first polarization state corresponds to a transverse electric (TE) mode
  • the second polarization state corresponds to a transverse magnetic (TM) mode
  • a slanted angle, a height or a refractive index of the plurality of first nanoscale elements is different from a slanted angle, a height or a refractive index of the plurality of second nanoscale elements.
  • the first metasurface grating including the plurality of first nanoscale elements is non-transmissive to the second light of the second polarization state.
  • the second metasurface grating including the plurality of second nanoscale elements is non-transmissive to the first light of the first polarization state.
  • an optical device includes a first polarizer configured to convert light into a first light of a first polarization state, a second polarizer configured to convert light into a second light of a second polarization state, and a waveguide configured to propagate the first light of the first polarization state and the second light of the second polarization state.
  • the optical device further includes a first metasurface grating disposed on the waveguide and including a plurality of first nanoscale elements, wherein the first nanoscale elements define a first polarization-dependent phase profile that transmits the first light of the first polarization state in a first direction, and a second metasurface grating disposed on the waveguide and including a plurality of second nanoscale elements, wherein the second nanoscale elements define a second polarization-dependent phase profile that transmits the second light of the second polarization state in a second direction different from the first direction.
  • the optical device includes a collimator configured to collimate the first light of the first polarization state and the second light of the second polarization state.
  • the waveguide includes an in-coupler and an out- coupler, at least a portion of the first metasurface grating is disposed on the out-coupler of the waveguide, and at least a portion of the second metasurface grating is disposed on the in coupler of the waveguide.
  • the first polarization state corresponds to a transverse electric (TE) mode
  • the second polarization state corresponds to a transverse magnetic (TM) mode
  • a slanted angle, a height or a refractive index of the plurality of first nanoscale elements is different from a slanted angle, a height or a refractive index of the plurality of second nanoscale elements.
  • the first metasurface grating including the plurality of first nanoscale elements is non-transmissive to the second light of the second polarization state.
  • the second metasurface grating including the plurality of second nanoscale elements is non-transmissive to the first light of the first polarization state.
  • FIG. 1 A schematically illustrates a grating coupler for augmented reality.
  • FIG. 1B illustrates a metasurface that causes a wavevector to be a function of angle of incidence.
  • FIG. 2 illustrates a field of view depending on a way that a metasurface alters wavevector for various angles of incidence.
  • FIG. 3 illustrates slanted pillars as examples of phase shifters of a metasurface.
  • FIG. 4A illustrates light phase as a function of incidence angle for various filling factors.
  • FIG. 4B illustrates light transmission as a function of incidence angle for various filling factors.
  • FIG. 5 illustrates an omni-angle resonator or filter device based on an angle-dependent metasurface.
  • FIG. 6(a) illustrates a schematic of an optical combiner based on polarization-dependent metagrating.
  • FIG. 6(b) illustrates a schematic of an out-coupler of a waveguide of the optical combiner.
  • FIG. 7(a) illustrates an FOV achieved by an out-coupler of a comparative diffractive grating.
  • FIG. 7(b) illustrates an FOV achieved by an out-coupler based on polarization-dependent metagrating.
  • FIG. 8(a) illustrates a unit cell of a TM (Transverse Magnetic)-pass grating.
  • FIG. 8(b) illustrates a unit cell of a TE (Transverse Electric)-pass grating.
  • FIG. 9(a) illustrates a diffraction efficiency of TE-pass gratings as a function of incident angles.
  • FIG. 9(b) illustrates a diffraction efficiency of TM-pass gratings as a function of incident angles.
  • FIG. 9(c) illustrates an overall diffraction efficiency in the transmission as a function of the output angles.
  • FIG. 10 illustrates transmission efficiencies at normal incidence, including transmission spectrum of TE-pass gratings, transmission spectrum of TM-pass gratings, and overall transmission.
  • At least some embodiments of the present disclosure relate to metasurface gratings (also referred to as metagratings) with angular-dependent phase profile.
  • Devices with angular-dependent metasurface gratings can be used to significantly increase the achievable field of view (FOV) of augmented reality devices, and can be used to achieve new types of optical devices.
  • FOV field of view
  • slanted pillars may achieve asymmetric angle-dependent phase with a significant tunability, and may be used to realize an angle-dependent phase profile of the metasurface.
  • some embodiments of the present disclosure relate to optical device designed for the visible region, by changing material composition, the disclosed technology can be adopted to other spectral regions, such as near-infrared region.
  • FIG. 1 A schematically illustrates a grating coupler for augmented reality.
  • free space incident light receives a parallel wavevector from the grating coupler 130 and then is guided by total internal reflection (TIR) in a transparent substrate 110, which can include, but is not limited to, glass.
  • the substrate 110 can be a waveguide for an augmented reality device.
  • the waveguide overlays augmented reality information on a view of a real-world environment.
  • the rays 115 and 120 respectively correspond to light of the same wavelength guided at the maximum and minimum angles (with respect to the direction of normal incidence).
  • the ray 115 is coupled out through a downstream grating 130.
  • the ray 120 is guided in the substrate by TIR.
  • the device can also function as a grating out-coupler if the light is fed from the waveguide due to reversibility.
  • the momentum of an incident photon is proportional to its wavevector.
  • the magnitude of the wavevector k is equal to 2p/l. where l is wavelength of the light wave.
  • Gratings and metasurfaces can impart a wavevector to a light beam, which is parallel to the surface with values equal to 2p/r and
  • the incident rays from a micro-display are guided by total internal reflection after diffraction through a grating patterned on top of a substrate.
  • some rays are guided by unfavorable large angles and are hardly coupled out by the exit grating. This is illustrated by the ray 115 in FIG 1A.
  • the largest guided angle may be specified to be smaller than a critical angle (e.g., about 72 degrees).
  • the minimal guided angle (corresponding to line 120 in FIG. 1A) may specified to be about equal to asin( /) , where n is the refractive index of the substrate.
  • the FOV is thus determined based on the difference in the angles of incidence Q corresponding to the maximal and minimal guided angles in the substrate.
  • the refractive index of the substrate is increased in order to increase FOV.
  • increasing the refractive index means changing the material of the substrate, which can significantly increase the cost and reduce optical performance of the device.
  • FIG. 1B illustrates a metasurface that causes a wavevector to be a function of angle of incidence.
  • the horizontal wavevector k provided by metasurface coupler 150 and a grating coupler 160 is a function of the angle of incidence Q.
  • Such an angle-dependent wavevector decreases the deflection angle of ray 115 of FIG. 1A and increases the deflection angle of ray 120 of FIG. 1A.
  • the metasurface provides less parallel momentum to the ray 115 and more momentum to the ray 120 compared to comparative gratings.
  • the increase of FOV is related to the parameter a in Eq. 1. According to the generalized law of refraction and reflection and the conditions of the maximal/minimal guided angles, the maximum angle and the minimum angles have relationships of:
  • the achievable FOV is determined by la, satisfying: n sin(72°)— 1.
  • FIG. 2 illustrates an FOV depending on a way that a metasurface alters wavevector according to Eq. 1 for various anges of incidence.
  • a horizontal FOV is a function of la .
  • Symmetric horizontal FOV is assumed in FIG. 2.
  • the values of the FOV function are numerically calculated based on a substrate with a refractive index of about 1.7. As shown in FIG.
  • the FOV can be increased by as much as three fold, for example.
  • the metasurface phase profile can be assumed to vary merely along at least one coordinate (e.g., x-coordinate). In some embodiments, the metasurface phase profile can vary along multiple directions.
  • the C(6) term in Eq. (9) offers an additional degree of freedom for tuning the required angular dispersion.
  • f(c, Q) at a given x-coordinate can be asymmetric with respect to Q.
  • slanted pillars can be used to introduce Bragg resonance for realizing asymmetric phase response.
  • Bragg resonances occurs when the following condition is satisfied:
  • the effective index n e ⁇ can be obtained by numerically solving Maxwell’s equations and is related to the slant angle of the slanted pillars, the incidence angle and the filling factor in combination.
  • the filling factor is defined as w/p, where w is the pillar width.
  • FIG. 3 illustrates slanted pillars as examples of phase shifters of a metasurface.
  • the metasurface 300 includes slanted pillars 310 disposed on a substrate 320.
  • the slanted pillars 310 can be, e.g., nanoscale structures (e.g., nanopillars).
  • 0 inc is the angle of incidence with respect to the surface normal.
  • 0 slant is the slant angle with respect to the surface normal.
  • the pillars 310 are slanted, which means that 0 slant is nonzero p is the grating period of the slanted pillars 310.
  • FIG. 4A illustrates the light phase change as a function of incidence angle for various filling factors.
  • the angular dispersion can be tuned from positive to negative. Relatively large angular dispersion can be achieved at even small filling factors.
  • FIG. 4B illustrates light transmission as a function of incidence angle for various filling factors. The resonance behavior is also manifested as a dip in the transmission spectrum as shown in FIG. 4B.
  • FIG. 5 illustrates an omni-angle resonator or filter device based on an angle-dependent metasurface.
  • the metasurface can be patterned on top of one or more optical resonators and/or one or more filters to render the functionalities of these devices substantially insensitive to incidence angles.
  • design or“designed” (e.g., as used in“design wavelength,”“design focal length” or other similar phrases disclosed herein) refers to parameters set during a design phase; which parameters after fabrication may have an associated tolerance.
  • a metasurface grating includes a substrate and multiple nanoscale elements disposed on the substrate.
  • the nanoscale elements define an angle- dependent phase profile that imparts a wavevector that varies depending on angles of incidence.
  • a cross-section of at least one nanoscale element is rectangular or other polygonal shape. In some embodiments, a cross-section of at least one nanoscale element is elliptical or circular. In some embodiments, a cross-section of nanoscale elements can have a 2-fold rotational symmetry, or more generally, an n-fold rotational symmetry where n is an integer that is 2 or greater than 2.
  • nanoscale elements are composed of a semiconductor, an oxide (e.g., a metal or non-metal oxide), a nitride (e.g., a metal or non-metal nitride), a sulfide (e.g., a metal or non-metal sulfide), a pure element, or a combination of two or more of these.
  • a substrate is transparent in the visible spectrum, such as a polymer substrate, a glass substrate or one including fused silica.
  • Suitable substrates that are transparent in the visible spectrum can have a light transmittance of at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 85%, at least about 90%, or at least about 95%, over the visible spectrum or a design or working wavelength in the visible spectrum.
  • a substrate is curved or flexible, which offer alternative functionalities, for example to adjust the image distance to the eye or to focus light.
  • nanoscale elements include a dielectric material.
  • suitable dielectric materials include metal and non-metal oxides (such as an oxide of aluminum (e.g., AI2O3), silicon (e.g., S1O2), hafnium (e.g., HfCh), zinc (e.g., ZnO), magnesium (e.g., MgO), or titanium (e.g., T1O2)), metal and non-metal nitrides (such as nitrides of silicon (e.g., S13N4), boron (e.g., BN), or tungsten (e.g., WN)), metal and non- metal sulfides, and pure elements (e.g., silicon for operation at near-infrared and mid-infrared wavelengths).
  • metal and non-metal oxides such as an oxide of aluminum (e.g., AI2O3), silicon (e.g., S1O2), hafnium (e.g., HfCh
  • nanoscale elements have aspect ratios (e.g., height/width) greater than about one, such as at least about 1.5: 1, at least about 2:1, at least about 3:1, at least about 4:1, or at least about 5: 1, and up to about 10: 1 or greater, or up to about 20: 1 or greater.
  • geometric dimensions (e.g., height/width/length or diameter/height) of nanoscale elements are sub-wavelength, such as about 800 nm or less, about 700 nm or less, or about 600 nm or less.
  • nanoscale elements are slanted nanopillars with a nonzero slant angle with respect to a surface normal of a metasurface grating.
  • the nonzero slanted angle is about 1 degree or greater, about 2 degrees or greater, about 5 degrees or greater, or about 10 degrees or greater, and up to about 45 degrees or greater, or up to about 50 degrees or greater.
  • AR augmented reality
  • a diffractive grating out-coupler can be used to progressively extract the light guided by TIR (total internal reflection) in the planar glass plate.
  • TIR total internal reflection
  • three layers of waveguide gratings corresponding to red, green and blue (RGB) light can be stacked together, for example. Each layer is designed to extract light at a specific spectral range.
  • the FOV in the diffractive grating based approaches can depend on the waveguide refractive index. For example, for a waveguide refractive index of about 1.7, the horizontal FOV is less than about 40°. In contrast, the presently disclosed technology can achieve a horizontal FOV as large as about 67 ° , for example, using polarization-dependent metagratings. Similar to polarization division multiplexing in optical fiber communications where two channels with orthogonal polarizations are used to double the information capacity, certain presently disclosed technology increases the FOV by encoding the left and right FOV into two orthogonal polarization channels, TE (Transverse Electric) and TM (Transverse Magnetic).
  • TE Transverse Electric
  • TM Transverse Magnetic
  • Polarization-dependent metagratings which include subwavelength patterned nanostructures, are designed to selectively extract TE or TM light respectively (also referred to as TE-pass grating and TM-pass grating respectively).
  • the out-coupler includes alternate columns of TE-pass and TM-pass gratings.
  • a one-dimensional (1D) eyebox expansion e.g., horizontal FOV
  • the design approach can be generalized to full-color two-dimensional 2D eyebox expansion by additional diffractive optical elements that redirect the guided light at about 90° and stacking multipole layers (e.g., three layers for RGB channels respectively) of waveguides together.
  • At least some embodiments of the present disclosure relate to a waveguide display design based on polarization-dependent metagratings.
  • FOV overall horizontal field of view
  • Metagratings that selectively diffract out TE or TM polarized light are designed and simulated using, e.g., rigorous coupled wave analysis (RCWA).
  • RCWA rigorous coupled wave analysis
  • High polarization selectivity can be achieved, with minimal crosstalk between the two channels.
  • the transmission spectrum at normal incidence is calculated to assess the see- through effect. Remaining challenges such as fabrication issues are disclosed.
  • the multiplexing information in the polarization domain in waveguide displays may increase the FOV in AR devices.
  • FIG. 6(a) illustrates a schematic of an optical combiner based on polarization- dependent metagrating.
  • the optical engine includes a microdisplay, two orthogonal linear polarizers (e.g., X polarizer and Y polarizer) covering the left and right halves of the display respectively, and a collimator.
  • the waveguide includes an in-coupler and an out-coupler, which are responsible for coupling in and out the free space light to guided light respectively.
  • the waveguide can be, e.g., a high-index glass plate.
  • the disclosed in-coupler and out-coupler of the waveguide imparts different transverse momentum to TE and TM light selectively.
  • Linear polarizers that transmit X (TM) polarization or Y (TE) polarization are placed in front of the right or left part of the microdisplay panel respectively.
  • TM transmit X
  • TE Y
  • TIR time IR
  • FIG. 6(b) illustrates a schematic of an out-coupler of the waveguide.
  • TM-pass gratings can be spatially multiplexed together.
  • the zoom-in view shows that the two types of metagratings are patterned with different nanostructures and/or have different grating periods.
  • the TE-pass grating diffracts out TE light, and reflects the TM light so that the TM light continues propagating in the waveguide.
  • the TM-pass grating diffracts out TM light, and reflects the TE light so that the TE light continues propagating in the waveguide.
  • the polarization selectivity is achieved by spatially interleaving two types of metagratings, TE-pass and TM-pass gratings as shown in FIG. 6(b).
  • the two types of metagratings have different grating periods, therefore TE and TM light from the same incident angle is diffracted to different output angles.
  • the metagratings are designed to diffract out light of a specific polarization, and reflect back the other polarization as shown in FIG. 6(b).
  • FIG. 7(a) illustrates an FOV achieved by an out-coupler of a comparative diffractive grating.
  • TE light and TM light share the same FOV.
  • the light guided in the waveguide is constrained within a cone 9 inc min ⁇ 9 inc max .
  • the output angle is given by the grating equation: l
  • the maximum achievable FOV can be less than about 40° as long as the center of the FOV, which equals (9 0Ut min + 9 0Ut max )/2, is less than about 15° away from the normal direction.
  • FIG. 7(b) illustrates an FOV achieved by an out-coupler based on polarization- dependent metagrating.
  • TE light and TM light are diffracted to two separate viewing zones.
  • the overall FOV is increased.
  • the out-coupler imparts different transverse momentums to TE light and TM light.
  • the grating periods of the TE-pass and TM- pass grating are denoted by PTE and PTM respectively.
  • PTE is larger than P TM so that TE and TM light is diffracted to the right and left region respectively.
  • the grating equations become
  • FIG. 8(a) illustrates a unit cell of a TM-pass grating.
  • the slanted ridge has a refractive index of about 2.4.
  • H t about 350 nm
  • W about 280 nm.
  • FIG. 8(b) illustrates a unit cell of a TE-pass grating.
  • the rectangular ridges have a refractive index of about 1.716.
  • H 2 about 250 nm
  • W 1 about 90 nm
  • W 2 about 40 nm.
  • the TM-pass grating is slanted at about 40° to increase the TM light out- coupling efficiency at large incident angles.
  • the TE-pass grating includes at least two rectangular ridges within each unit cell.
  • the two metagratings have different slanted angles, heights, and/or refractive indices.
  • advanced metagrating optimization methods e.g. topological optimization
  • the grating diffraction efficiency for TE and TM light into each order can be calculated using, e.g., rigorous coupled wave analysis (RCWA).
  • the transmitted lst order is the desired out-coupling order.
  • the reflected 0th order carries the guided light to propagate down the waveguide. All other diffraction orders may be deemed undesired, in some embodiments.
  • FIG. 9(a) illustrates a diffraction efficiency of TE-pass gratings as a function of incident angles (e.g., guided angles inside the waveguide).
  • FIG. 9(b) illustrates a diffraction efficiency of TM-pass gratings as a function of incident angles (e.g., guided angles inside the waveguide).
  • the transmitted lst order of TM (TE) light is negligible in TE (TM) pass gratings, in accordance with the specified polarization selectivity.
  • the diffraction power into undesired orders can be comparable or even larger than the desired out-coupling order, which may be further improved to avoid efficiency loss. Although they may be a source of loss, the undesired orders do not necessarily introduce undesirable ghost images, as the undesired orders are mostly reflected at an angle smaller than TIR and leave the waveguide at the backside (the environment side).
  • FIG. 9(c) illustrates an overall diffraction efficiency in the transmission (including transmissions of both TE-pass grating and TM-pass grating) as a function of the output angles.
  • the left (right) half of the FOV contains TM (TE) light only.
  • TM TE
  • There is some residue undesired higher order e.g., transmitted 2nd order
  • the residue undesired higher order falls outside of the FOV and does not interfere with the virtual image.
  • see-through effect is another performance criterion for optical combiners.
  • the real world image is desired to be minimally altered (ideally unaltered) after passing through the optical combiner.
  • the see-through performance of the metagratings can be characterized by the transmission efficiency under normal incidence.
  • FIG. 10 illustrates transmission efficiencies at normal incidence, including transmission spectrum of TE-pass gratings, transmission spectrum of TM-pass gratings, and overall transmission.
  • the overall transmission which is averaged over TE and TM light through TE and TM pass gratings, is relatively flat across the visible spectrum, with corresponds to a mean transmission efficiency of at least about 75%.
  • the TE and TM pass gratings can be fabricated separately.
  • the unit cell designs may be designed with the same material, height and slanted angle for both TE and TM pass gratings, so that they can be fabricated in one fabrication step.
  • the residue undesired orders introduce loss of efficiency, and can to be suppressed.
  • a uniform diffraction efficiency may be achieved, for a better use of the display’s dynamic range and viewing experience.
  • the terms“approximately,”“substantially,”“substantial” and “about” are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation.
  • the terms can refer to a range of variation less than or equal to ⁇ 10% of that numerical value, such as less than or equal to ⁇ 5%, less than or equal to ⁇ 4%, less than or equal to ⁇ 3%, less than or equal to ⁇ 2%, less than or equal to ⁇ 1%, less than or equal to ⁇ 0.5%, less than or equal to ⁇ 0.1%, or less than or equal to ⁇ 0.05%.
  • two numerical values can be deemed to be “substantially” the same if a difference between the values is less than or equal to ⁇ 10% of an average of the values, such as less than or equal to ⁇ 5%, less than or equal to ⁇ 4%, less than or equal to ⁇ 3%, less than or equal to ⁇ 2%, less than or equal to ⁇ 1%, less than or equal to ⁇ 0.5%, less than or equal to ⁇ 0.1%, or less than or equal to ⁇ 0.05%.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)

Abstract

La présente invention concerne un dispositif optique comprenant un premier réseau de métasurfaces et un second réseau de métasurfaces pouvant réaliser un grand champ de vision (FOV). Le premier réseau de métasurfaces comprend une pluralité de premiers éléments à l'échelle nanométrique. Les premiers éléments à l'échelle nanométrique définissent un premier profil de phase dépendant de la polarisation qui transmet une première lumière d'un premier état de polarisation dans une première direction. Le second réseau de métasurfaces comprend une pluralité de seconds éléments à l'échelle nanométrique. Les seconds éléments à l'échelle nanométrique définissent un second profil de phase dépendant de la polarisation qui transmet une seconde lumière d'un second état de polarisation dans une seconde direction différente de la première direction.
PCT/US2019/012205 2018-01-04 2019-01-03 Métasurfaces dépendant de l'angle ou dépendant de la polarisation avec grand champ de vision WO2019136166A1 (fr)

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US201862613668P 2018-01-04 2018-01-04
US62/613,668 2018-01-04
US201862660812P 2018-04-20 2018-04-20
US62/660,812 2018-04-20

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CN110568624A (zh) * 2019-08-15 2019-12-13 复旦大学 基于角度色散原理的偏振转化装置
CN110703371A (zh) * 2019-10-14 2020-01-17 江西师范大学 半导体超表面电磁波吸收器及其制备方法
CN110794661A (zh) * 2019-11-22 2020-02-14 武汉大学 基于叠层超表面实现双通道纳米印刷和双通道全息的方法
CN111007585A (zh) * 2019-12-06 2020-04-14 武汉大学 消除零级的超表面正弦光栅及其设计方法
US10795168B2 (en) 2017-08-31 2020-10-06 Metalenz, Inc. Transmissive metasurface lens integration
US20210028215A1 (en) * 2019-07-26 2021-01-28 Metalenz, Inc. Aperture-Metasurface and Hybrid Refractive-Metasurface Imaging Systems
WO2021035789A1 (fr) * 2019-08-28 2021-03-04 诚瑞光学(常州)股份有限公司 Dispositif d'affichage à réalité augmentée à guide d'ondes
WO2021061228A1 (fr) * 2019-09-27 2021-04-01 Microsoft Technology Licensing, Llc Métasurface à moment cinétique non linéaire
WO2021061227A1 (fr) * 2019-09-27 2021-04-01 Microsoft Technology Licensing, Llc Système d'expansion de champ de vision
CN113466984A (zh) * 2021-06-30 2021-10-01 暨南大学 基于双柱电介质超表面的偏振器件
CN114488525A (zh) * 2022-04-15 2022-05-13 中国科学院光电技术研究所 一种超构表面成像系统、设计方法和探测器
CN115201959A (zh) * 2021-04-13 2022-10-18 宁波舜宇车载光学技术有限公司 光波导片、器件以及近眼显示系统
WO2022258885A1 (fr) * 2021-06-10 2022-12-15 Dispelix Oy Agencement de guide d'ondes optique à capacité améliorée
US11579253B2 (en) * 2018-11-09 2023-02-14 The Charles Stark Draper Laboratory, Inc. Dual-polarization LiDAR systems and methods
WO2023064106A1 (fr) * 2021-10-15 2023-04-20 Applied Materials, Inc. Architectures de métasurface multicouches avec adaptation d'impédance
WO2023061919A1 (fr) * 2021-10-12 2023-04-20 Interdigital Ce Patent Holdings, Sas Agrandisseurs de pupille en couleur à champ de vision vertical élevé
US11906698B2 (en) 2017-05-24 2024-02-20 The Trustees Of Columbia University In The City Of New York Broadband achromatic flat optical components by dispersion-engineered dielectric metasurfaces
US11927769B2 (en) 2022-03-31 2024-03-12 Metalenz, Inc. Polarization sorting metasurface microlens array device
WO2024066608A1 (fr) * 2022-09-29 2024-04-04 深圳迈塔兰斯科技有限公司 Procédé et appareil de conception de métasurface, et dispositif électronique

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US11906698B2 (en) 2017-05-24 2024-02-20 The Trustees Of Columbia University In The City Of New York Broadband achromatic flat optical components by dispersion-engineered dielectric metasurfaces
US11988844B2 (en) 2017-08-31 2024-05-21 Metalenz, Inc. Transmissive metasurface lens integration
US11579456B2 (en) 2017-08-31 2023-02-14 Metalenz, Inc. Transmissive metasurface lens integration
US10795168B2 (en) 2017-08-31 2020-10-06 Metalenz, Inc. Transmissive metasurface lens integration
US11579253B2 (en) * 2018-11-09 2023-02-14 The Charles Stark Draper Laboratory, Inc. Dual-polarization LiDAR systems and methods
US20210028215A1 (en) * 2019-07-26 2021-01-28 Metalenz, Inc. Aperture-Metasurface and Hybrid Refractive-Metasurface Imaging Systems
US11978752B2 (en) 2019-07-26 2024-05-07 Metalenz, Inc. Aperture-metasurface and hybrid refractive-metasurface imaging systems
CN110568624B (zh) * 2019-08-15 2021-06-04 复旦大学 基于角度色散原理的偏振转化装置
CN110568624A (zh) * 2019-08-15 2019-12-13 复旦大学 基于角度色散原理的偏振转化装置
WO2021035789A1 (fr) * 2019-08-28 2021-03-04 诚瑞光学(常州)股份有限公司 Dispositif d'affichage à réalité augmentée à guide d'ondes
US11467406B2 (en) 2019-09-27 2022-10-11 Microsoft Technology Licensing, Llc Field of view expanding system
WO2021061228A1 (fr) * 2019-09-27 2021-04-01 Microsoft Technology Licensing, Llc Métasurface à moment cinétique non linéaire
WO2021061227A1 (fr) * 2019-09-27 2021-04-01 Microsoft Technology Licensing, Llc Système d'expansion de champ de vision
US11448883B2 (en) 2019-09-27 2022-09-20 Microsoft Technology Licensing, Llc Non-linear angular momentum metasurface
CN110703371A (zh) * 2019-10-14 2020-01-17 江西师范大学 半导体超表面电磁波吸收器及其制备方法
CN110794661B (zh) * 2019-11-22 2020-10-30 武汉大学 基于叠层超表面实现双通道纳米印刷和双通道全息的方法
CN110794661A (zh) * 2019-11-22 2020-02-14 武汉大学 基于叠层超表面实现双通道纳米印刷和双通道全息的方法
CN111007585A (zh) * 2019-12-06 2020-04-14 武汉大学 消除零级的超表面正弦光栅及其设计方法
CN115201959A (zh) * 2021-04-13 2022-10-18 宁波舜宇车载光学技术有限公司 光波导片、器件以及近眼显示系统
WO2022258885A1 (fr) * 2021-06-10 2022-12-15 Dispelix Oy Agencement de guide d'ondes optique à capacité améliorée
CN113466984A (zh) * 2021-06-30 2021-10-01 暨南大学 基于双柱电介质超表面的偏振器件
CN113466984B (zh) * 2021-06-30 2023-11-17 暨南大学 基于双柱电介质超表面的偏振器件
WO2023061919A1 (fr) * 2021-10-12 2023-04-20 Interdigital Ce Patent Holdings, Sas Agrandisseurs de pupille en couleur à champ de vision vertical élevé
WO2023064106A1 (fr) * 2021-10-15 2023-04-20 Applied Materials, Inc. Architectures de métasurface multicouches avec adaptation d'impédance
US11927769B2 (en) 2022-03-31 2024-03-12 Metalenz, Inc. Polarization sorting metasurface microlens array device
CN114488525A (zh) * 2022-04-15 2022-05-13 中国科学院光电技术研究所 一种超构表面成像系统、设计方法和探测器
WO2024066608A1 (fr) * 2022-09-29 2024-04-04 深圳迈塔兰斯科技有限公司 Procédé et appareil de conception de métasurface, et dispositif électronique

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