Optical device with zone-folded super surface

Abstract

Optical device with zone-folded super surface. An optical combiner is disclosed that includes a first layer having a periodic two-dimensional arrangement of structures arranged to support resonance for an input signal of a target wavelength, wherein the structures have a first refractive index. A second layer overlies the structures on the first layer, wherein the second layer includes a second material having a second refractive index, and wherein a difference between the first refractive index and the second refractive index measured at 587.5 nm is less than about 1.5. The periodic arrangement of structures is configured such that the optical combiner produces an output signal having a reflection peak for the input signal incident on the first layer from air at a tilt elevation angle greater than about 20°, wherein the reflection peak has an average reflection greater than about 50% within ±5° of the elevation angle.

Description

Background Technology

[0001] Automotive head-up displays (HUDs) provide drivers with real-time information in a convenient and safe manner. (Reference) Figure 1 As illustrated in the diagram, the vehicle's HUD system 10 includes an optical combiner 12 situated between an outer windshield glass layer 14 and an inner windshield glass layer 16. A projector 18, including a light source (such as a laser or LED), emits polarized narrowband red light 20, green light 22, and blue light 24 incident at a selected tilted incident elevation angle θ onto a first surface 13 of the optical combiner 12. The first surface 13 of the optical combiner 12 reflects the red / green / blue (RGB) light toward the eye 26 of an observer (vehicle driver) in a specular manner to create the desired virtual image. While highly reflective for the narrowband polarized RGB light 20, 22, 24 at the elevation angle θ, the combiner 12 should also be highly transmissive for the unpolarized broadband ambient light 28 incident on its second surface 15 to provide high transparency for the external view observed by the observer 26 through the windshield.

[0002] The combiner 12 should be highly transmissive to light arriving through the windshield, except for light at a small but limited angle from three selective wavelengths near the red, green, and blue wavelengths emitted by the projector. Low-cost, mass-producible materials are needed for the HUD display combiner that provide high transmissivity to narrow-band reflections and unpolarized ambient light for polarized input signals at an angle of incidence. Summary of the Invention

[0003] Traditional diffraction gratings are angle-dependent, meaning that the resonant wavelength of the output signal changes as the incident angle of the input signal changes. To reduce the angular variation of the reflection resonance from the diffraction grating, the spectral linewidth of the resonance can be controlled, resulting in a broader wavelength band with wider peaks. In some examples, this poor angular tolerance can reduce the broadband transmission of the diffraction grating and alter the hue of the output signal.

[0004] In one aspect, this disclosure relates to an optical device that uses a perturbation arrangement of periodic structures to flatten the angular response of a resonance effect while providing narrow-wavelength reflection resonance. In some examples, the perturbation structure can generate a band output signal at a desired incident angle through a narrower reflection band compared to a conventional diffraction grating.

[0005] In some examples, the optical device includes an optical combiner comprising a first structured layer of material having a first refractive index. The first structured layer comprises a structured surface having a periodic two-dimensional arrangement of structures (such as an array of recesses). A second layer of material having a second refractive index covers the structured surface and occupies at least a majority of the volume of each of the structures. The difference between the first and second refractive indices, measured at 587.5 nm, is less than about 1.5. For polarized or unpolarized light incident on the structured surface at an elevation angle greater than about 20° (±1°), the optical combiner can provide an output signal having one or more different narrowband reflection peaks (each having an average reflection greater than about 50%), and the average reflection peak in the output signal can be provided within a range of ±10°, ±5°, or ±3° of the elevation angle.

[0006] The optical combiner disclosed herein utilizes inexpensive and widely available materials and can be manufactured at a relatively low cost and on a large scale using, for example, a roll-to-roll manufacturing process.

[0007] In one aspect, this disclosure relates to an optical combiner comprising a first layer having a periodic two-dimensional arrangement of structures arranged to support resonance for an input signal of a target wavelength, wherein the structures have a first refractive index. A second layer covers the structures on the first layer, wherein the second layer comprises a second material having a second refractive index, and wherein the difference between the first refractive index and the second refractive index, measured at 587.5 nm, is less than about 1.5. The periodic arrangement of the structures is configured such that the optical combiner produces an output signal with a reflection peak for an input signal incident on the first layer from air at an elevation angle greater than about 20°, wherein the reflection peak has an average reflection of greater than about 50% over a range of ±5° of the elevation angle.

[0008] In another aspect, this disclosure relates to a windshield for a vehicle, the windshield including an outer glass layer, an inner glass layer, and an optical combiner film between the outer and inner glass layers. The optical combiner film includes a first layer having a periodic two-dimensional arrangement of a structure configured to support resonance for an input signal of a target wavelength, wherein the structure has a first refractive index; and a second layer covering the structure on the first layer, wherein the second layer includes a second material having a second refractive index, and wherein the difference between the first and second refractive indices, measured at 587.5 nm, is less than about 1.5. The periodic arrangement of the structure is configured such that the optical combiner produces an output signal with a reflection peak for an input signal incident on the first layer from air at an elevation angle greater than about 20°, wherein the reflection peak has an average reflection of greater than about 50% within ±5° of the elevation angle.

[0009] In another aspect, this disclosure relates to a head-up display (HUD) system comprising a computer having a processor that generates output including HUD display data; and a projector unit interfaced with the computer, wherein the projector unit includes a laser that emits a narrowband red / green / blue (RGB) input signal onto a windshield for display by an observer. The windshield includes an outer glass layer, an inner glass layer, and an optical combiner film between the outer and inner glass layers. The optical combiner film includes a first layer having a periodic two-dimensional arrangement of structures arranged to support resonance for an input signal of a target wavelength, wherein the structures have a first refractive index; and a second layer covering the structures on the first layer, wherein the second layer includes a second material having a second refractive index, and wherein the difference between the first and second refractive indices measured at 587.5 nm is less than about 1.5. The periodic arrangement of the structure is configured such that the optical combiner produces an output signal with a reflection peak for the RGB input signal incident on the first layer from air at an elevation angle greater than about 20°, wherein the reflection peak has an average reflection of greater than about 50% within ±5° of the elevation angle.

[0010] In another aspect, this disclosure relates to an optical combiner film comprising a structured layer covered by a capping layer. The structured layer comprises a periodic lattice of regularly repeating recesses, wherein the recessed lattice has perturbed hexagonal cell elements, and wherein the difference between the refractive index of the structure and the refractive index of the capping layer, measured at 587.5 nm, is less than about 1.5. The periodic lattice is configured such that the optical combiner film produces an output signal with a reflection peak for an input signal incident on the structured layer from air at an elevation angle greater than about 20°, wherein the reflection peak has an average reflection greater than about 50% over a range of ±5° of that elevation angle.

[0011] In another aspect, this disclosure relates to a method for manufacturing an optical combiner film. The method includes forming a first layer on a polymer support film, wherein the first layer comprises a periodic arrangement of recesses and has a perturbed arrangement of hexagonal cells, and wherein the first layer comprises a material having a first refractive index; and applying a capping layer on the first layer, wherein the capping layer comprises a material having a second refractive index, and wherein the difference between the first refractive index and the second refractive index, measured at 587.5 nm, is less than about 1.5. This structure in the first layer is configured such that the optical combiner film produces an output signal with a reflection peak for an input signal incident on the first layer from air at an elevation angle greater than about 20°, wherein the reflection peak has an average reflection of greater than about 50% within a ±5° range of the elevation angle.

[0012] In another aspect, this disclosure relates to an optical combiner comprising: a first structured layer of a first material having a first refractive index, wherein the first structured layer includes a first periodic two-dimensional arrangement of structures arranged to support resonance for input signals of a first target wavelength and a second target wavelength; and a second structured layer of a second material having a second refractive index, wherein the second structured layer includes a second periodic two-dimensional arrangement of structures arranged to support resonance for input signals of a third target wavelength different from the first and second target wavelengths, wherein the first and second structured layers are stacked on top of each other such that light incident on the first structured layer is continuously diffracted through the first and second structured layers. The first and second structured layers are encapsulated in a third material having a third refractive index such that the refractive index difference between each of the first and second refractive indices measured at 587.5 nm and the third refractive index is less than about 1.5. The structure in the first and second structured layers is configured such that the optical combiner produces an output signal with three reflection peaks for an input signal incident from air at an elevation angle greater than about 20° on a first periodic arrangement of the structure, wherein the three reflection peaks have an average reflection greater than about 50% within ±5° of the elevation angle.

[0013] Details of one or more embodiments of the present invention are shown in the following drawings and description. Other features, objects, and advantages of the invention will become apparent from the description and drawings, as well as from the claims. Attached Figure Description

[0014] Figure 1 This is a schematic cross-sectional view of a head-up display (HUD) used in vehicles.

[0015] Figure 2 These are a series of graphs illustrating conventional methods for broadening the reflection peaks so that the diffraction grating can function over a wider angular range.

[0016] Figure 3 These are a series of graphs illustrating the method of this disclosure for improving the angular tolerance of periodic structures by providing flat reflections at a selected tilt angle.

[0017] Figures 4A to 4B This includes schematic diagrams and reflectivity graphs of an idealized optical combiner suitable for use in devices such as HUDs and ARs. These devices require broadband transmission and sharp resonant reflection.

[0018] Figures 4C to 4DThis includes a schematic diagram and reflectivity graph showing that, in HUD and AR applications, the angular response of the optical combiner should be sufficiently tolerant so that the resonant dispersion is less than the linewidth Δθ within the field of view (FoV).

[0019] Figure 5 shows the quasi-constrained state (QBIC) band in a folded flat continuum for symmetry-protected momentum. Figure 5A The actual spatial geometry of the target structure is shown, which consists of etched and filled structures with a low refractive index n. L The material has a refractive index n H The lattice is composed of flat plates. The lattice exhibits hexagonal symmetry when the perturbation value δ = 0 (for the selected...). And otherwise it has rectangular symmetry.

[0020] Figure 5B yes Figure 5A The reciprocal lattice of the device depicts how different regions of the undisturbed FBZ fold into the FBZ when perturbed. Unloaded points refer to high-symmetry points in the undisturbed lattice, while loaded points refer to points in the perturbed lattice.

[0021] Figure 5C This illustrates the TE mode (characterized by H) for a flat plate of finite thickness. z An exemplary strip diagram shows the folding at K points at Γ and M. x A flat band located between θ points. The red dashed line indicates the area at θ. op The incident light rays. The light-shaded areas correspond to the constrained modes (under the light), while the white and dark-shaded areas correspond to the radiation continuums that support one and more diffraction modes, respectively.

[0022] Figure 5D This illustrates how folding the K-point pattern is achieved by changing the ratio a. y / a x And control over situations that become possible. Figures 5C to 5D The calculation is performed using a 2D plane wave expansion method, where the effect of out-of-plane dimensions is approximated by using an effective refractive index of n = 2.2.

[0023] Figure 6A This is a schematic diagram of the metasurface and excitation geometry of the optical combiner in Example 1, wherein the thickness of the TiO2 layer is 120 nm.

[0024] Figure 6B The design of the optical combiner of Embodiment 1 is shown, wherein a x =231nm, a y =386nm, D=143nm, and δ=66nm.

[0025] Figure 6C yes Figure 6B SEM image of a top perspective view of the fabricated metasurface, without the capping polymer layer ( Figure 6A (120 in the middle). The scale bar is 300 nm.

[0026] Figures 6D to 6E It is a graph of the analog color-coded transmission spectrum of the grating relative to the incident polarization, the elevation angle θ, and the wavelength for p-polarized and s-polarized signals. Figures 6F to 6G yes Figures 6D to 6E The experimental measurement version.

[0027] Figure 6H This is a graph of the p-polarized transmission spectrum of the metasurface of Example 1 at three selected angles.

[0028] Figure 6I This is a graph of the experimentally measured non-polarized average transmission relative to the elevation angle θ, obtained by using the spectral average value of the calibration plot in panel 6D-E.

[0029] Figure 6J The graph shows the experimentally measured reflection and transmission spectra of the metasurface of Example 1 at an elevation angle θ = 58°, relative to wavelength.

[0030] Figure 7A This is a diagram of the actual space lattice of the optical combiner of Example 2, which has four rectangular apertures with dimensions of 45 × 110 nm, rotated at angles α1, α1+90°, α2, α2+90°. The plate has a height H = 180 nm and a lattice constant of a. x =240nm and a y =277nm.

[0031] Figure 7B The device of Example 2 is for the abnormal quasi-momentum k c The reciprocal lattice view of the folded region.

[0032] Figures 7C to 7D These are calculated reflectance curves for right-circularly polarized (RCP) and left-circularly polarized (LCP) light in the blue region, respectively, for devices with α1 = 45° and α2 = 0°.

[0033] Figure 8A This is a schematic diagram of an embodiment of the optical combiner of the present disclosure, including cascaded structured surfaces, each structured surface including a two-dimensional arrangement of recessed perturbations.

[0034] Figure 8B yes Figure 8A A graph of the 0th order reflectivity of one of the structured surfaces in a cascaded configuration at an angle of incidence, wherein the arrangement of the recesses is configured to provide an output signal with two resonant peaks.

[0035] Figure 8C yes Figure 8A A graph of the 0th order reflectivity of one of the structured surfaces in a cascaded arrangement at an angle of incidence, wherein the arrangement of the recesses is configured to provide an output signal with a single resonant peak.

[0036] Figure 8D It is incident at an oblique angle of incidence on Figure 8A A graph showing the 0th order reflectivity of TM-polarized light on a combined cascade structure of an optical combiner.

[0037] Figure 8E yes Figure 8A The graph shows the 0th order reflectivity of the optical combiner.

[0038] Figure 8F yes Figure 8A The curve of the 0th order transmittance of the optical combiner.

[0039] Figure 9A This is a schematic diagram of an embodiment of a process for manufacturing the metasurface of this disclosure, the metasurface comprising a periodic arrangement of recessed perturbations.

[0040] Figure 9B This is a schematic diagram of an embodiment of a process for manufacturing the metasurface of this disclosure, the metasurface comprising a periodic arrangement of recessed perturbations.

[0041] Figure 10 This is a schematic cross-sectional view of an optical combiner film that can be laminated between glass sheets to form a windshield structure for vehicles or aircraft.

[0042] Figures 11A to 11B It is used to measure transmission ( Figure 11A ) and reflection ( Figure 11B A schematic diagram of the experimental setup used in Example 1. Figures 11A to 11B In the diagram, F1 and F2 are lenses with a focal length of f = 10 cm, LP represents a linear polarizer, BS1 and BS2 are beam splitters, and CCD is a camera.

[0043] In these accompanying figures, similar symbols represent similar elements. Detailed Implementation

[0044] Refer again Figure 1 If the input signal incident on the optical combiner 12 includes a narrow frequency channel (e.g., three wavelengths λ with narrow linewidths Δλ << λ), 红色 ±Δλ、λ 绿色 ±Δλ and λ 蓝色 Given a discrete set of ±Δλ), the response of the beam splitter can be modified to be spectrally selective so that ηart (λ 红色，绿色，蓝色 The efficiency is approximately 1, but 0 at all other wavelengths. In this way, the overall efficiency of external information can also be approximately one. For example, a guided-mode resonance (GMR) filter can be configured to generate a robust command within the resonant bandwidth Δλ via ripple depth (deeper ripples increase Δλ). However, in conventional GMR filters, in addition to spectral selectivity, the dispersion ω of the guided mode... res (k) also imparts strong angular selectivity, such that for a specific frequency ω, the reflectivity only increases when ω = ω res The single wave vector k of (k) satisfies R(ω,k)≈1.

[0045] refer to Figure 2 For abnormal incident angles, the dispersion of a conventional diffraction grating has an approximate form ω. res (k)=ω0+v g k, where ω0 is the resonant frequency under normal incidence and v g ≈c / n eff The group velocity of the guided mode (c is the speed of light in a vacuum and n) eff It is the effective exponent of the guiding mode (of order one). Therefore, for the resonance linewidth Δω = ω0 / Q (where Q is the Q factor characterizing spectral selectivity), the angular tolerance of the GMR (defined in this paper as the width of the angular range where the reflection is at least 50% of the maximum reflection) is Δθ ≈ n. eff / Q.

[0046] In conventional diffraction grating structures such as GMR filters, a wide spectral bandwidth is required to achieve a large field of view (FoV), which is related to high η. ext The desired narrow bandwidth directly conflicts with this. Alternatively, FoV can be extended by non-periodic patterning to spatially offset the resonant frequency to offset the angle dependence. However, for both manufacturing feasibility and mounting tolerances, periodic structures are highly preferred for compatibility with scalable methods such as roll-to-roll fabrication and nanoimprint lithography.

[0047] Now for reference Figure 3The optical combiner disclosed herein utilizes a first structured layer having a periodic two-dimensional arrangement of structures configured to support resonance for an input signal at a target wavelength. The first structured layer is covered by a second layer, and the difference in refractive index between the first and second layers is less than about 1.5, as measured at 587.5 nm. The periodic arrangement of the structures is configured such that the optical combiner produces an output signal with a reflection peak for an input signal incident from air at an angle greater than about 20° on the first layer, wherein the reflection peak has an average reflection greater than about 50% over a range of ±10° from the target wavelength. In this application, the average reflection measurement does not include Fresnel reflections from adjacent surfaces or layers (such as glass layers).

[0048] In some examples, the structure in the first layer is a quasi-constrained state (QBIC) structure in a continuum, which produces resonances that can be precisely controlled by reducing perturbations through symmetry rather than the ripple depth utilized in GMR devices. In addition to the symmetry-controlled Q factor (the magnitude of the perturbation δ follows Q∝1 / δ), 2 QBICs possess polarization dependence capable of reflecting symmetry control for any desired polarization, and the polarization control of flat optical filters can even be extended to the manipulation of circular polarization states. In some examples, QBICs are also compatible with high exponential contrast systems, in which case large in-plane Bragg scattering can produce flat band structures with increased angular tolerance (reduced angular selectivity).

[0049] Specifically, QBIC is usually well approximated by having a parabolic band structure, following a second-order Taylor expansion ω. res (k)≈ω0+b(kk c ) 2 / 2, where k c It is the momentum whose first derivative vanishes and b is a unit m. 2 Taylor expansion coefficients / s. In this case, when θ op =sin -1 (k c When operating near c / ω0), the angular tolerance of the resonant reflectivity has the form Therefore, not only the angular tolerance is affected by the Q factor (Q -1 / 2 Instead of Q -1 ) allows for more favorable scaling, and parameter b also provides independent degrees of freedom to manage the trade-off between angular selectivity and spectral selectivity, and can vary within several orders of magnitude (compared to n). eff compared to).

[0050] Unfortunately, due to symmetry, the momentum k that causes the first derivative to disappear c (Usually corresponds to edge-trimmed mode) with a normal upper limit above normal incidence k. c=0, or k at the edge of the first Brillouin zone (FBZ) c = ±π / a (where a is the lattice constant). The former would require operation under normal incident conditions, which is forbidden for optical combiners, and the latter would be under the light (in which case the mode is constrained and cannot resonate reflected light) or above the diffracted line (in which case the parasitic diffraction order would significantly reduce η). art Furthermore, it potentially introduces unwanted diffraction rainbow effects that distort external information. The "unexpected" mixing of patterns between two unrelated q-BICs can occur at any k... c The lower bandgap is opened, but (i) the resulting band depends not on Bragg scattering but on the strength of mode coupling, and therefore b may not be arbitrarily small; (ii) the phenomenon depends on “accidental” alignment between the two modes, thus reducing robustness from a design and practical (manufacturing) perspective; and (iii) it inherently requires the presence of additional resonances, thus reducing… Furthermore (iv) it increases the complexity of controlling the linewidth and polarization characteristics of the QBIC. Conversely, controlling k directly based on symmetry... c The solution will address these limitations while offering advantages of the spectral separation QBIC in terms of lifespan and polarization control.

[0051] The optical combiner disclosed herein utilizes a zone-folding method based on lattice perturbations, which provides robust control over the Q-factor, polarization state, and operating angle of band-edge modes. In the arrangement of the structured layers in this disclosure, a non-rectangular lattice is transformed into a rectangular lattice, and the Bragg local modes at the edges of the FBZ are folded into non-zero momentum within the FBZ, the value of which is fixed by the discrete translational symmetry of the lattice. By stretching or compressing the lattice in a direction orthogonal to the incident plane, the momentum, and thus the incident angle of the band-edge modes, can be tuned.

[0052] Because the incident angle breaks the inverted symmetry of the system compared to normal incident excitation, the band-edge QBIC is compatible with extrinsic chirality and thus provides selectivity for resonant polarization states of any elliptic polarization, including full circular dichroism. Since the block-folded QBIC is periodic, subwavelength in size, and exhibits broadband transmission behavior, these structures provide a scalable platform for projection optics combiners and other AR displays, offering fidelity regarding external information as well as efficiency of the input signal and minimal impairment of FoV.

[0053] like Figure 4AAs illustrated in the schematic diagram, when used in the optical combiner components of an optical device such as a head-up display (HUD) system, the structured surfaces or cascaded metasurface sets of this disclosure emit up to three selected wavelengths (e.g., red, green, and blue) in a specular reflection manner. In some examples, in the HUD, the structured surfaces reject external information (represented by broadband light) only in these bands, while overriding the information projected by the projector in the HUD (whose convergence reaches the user). Figure 4B The operating angle θ for the selected wavelength is shown. op The characteristic reflectance spectrum below.

[0054] Figure 4C The angular response of an optical combiner utilizing the structured surface of this disclosure in an exemplary system is schematically depicted, wherein information is transmitted by the user via a HUD at an elevation angle θ. op Viewed from the center but with extrema opposite to the angle Δθ. Figure 4D Correspondingly, the performance of an optical combiner utilizing the structure of this disclosure for full FoV HUD images is described, wherein the spectral shift of the resonant peak is smaller than its linewidth, thereby maintaining enhanced reflectivity at all operating angles. Figure 4D The same requirements are not described in the orthogonal direction.

[0055] In some examples, to avoid double images from direct reflections from the air-glass interface, the external interface of the HUD system should have an anti-reflective coating. In some examples, the operating elevation angle θ op It should be at or near the Brewster angle (approximately 58°), thus requiring p-polarized light to be transmitted by the HUD and resonantly reflected by the metasurface.

[0056] Figure 5A An example is shown of how a perturbation applied to a hexagonal photonic crystal can produce a rectangular lattice. Figure 5A The dashed hexagons in the diagram represent cells of an undisturbed lattice, while the solid rectangles represent cells of a perturbed structure. Figure 5A The exemplary perturbation shown (which is not intended to be limiting) causes the lattice to be vertically offset by a distance δ every other row, and the structure of the perturbation arranged in an array of this type can be used to excite a target TE (transversely electric) or s-polarized lattice by TM (transverse magnetic) (p-polarized) light. In this application, TE-polarized light is characterized in that its electric field is perpendicular to the plane of incidence. For TE-polarized light, the magnetic field (always perpendicular to the electric field in an isotropic material) is therefore located in the plane of incidence.

[0057] exist Figure 5B The diagram depicts the result of perturbation in reciprocal space, where the undisturbed FBZ (dashed hexagonal) region is folded into the perturbed FBZ (solid rectangle) by translating the reciprocal lattice vector of the perturbed structure. Figure 5BIn the unperturbed FBZ, the modes at K points (where Bragg scattering is maximum in the hexagonal lattice) have folded to point k far from Γ. c and the edge of the FBZ far from the disturbance f In this application, point k refers to a sampling point in the FBZ of the material, that is, a specific region in the reciprocal space that is closest to the origin (0,0,0) (Γ point).

[0058] Therefore, devices subjected to such disturbances Figure 5C As shown in the exemplary strip diagram, the flat strip is k c Centered away from point Γ. In this case, the operating angle makes the incident light ray (shown as...) Figure 5C (The dashed line centered at ω0)

[0059]

[0060] Where k0 = 2π / λ, at ω0 (the resonant frequency is at k... c When it intersects with a flat zone, for a given lattice, this operating angle is obviously fixed by the resonant frequency. However, in the y-direction a y The lattice constant on and in the x-direction a x The ratio of the lattice constants on the crystal is f = a y / a x Can be used for tuning k f The individual degrees of freedom. We note that the hexagonal case corresponds to... Specifically, we discovered that in this more general case, the distance k f satisfy

[0061]

[0062]

[0063] Figure 5D The various choices for f along Γ-M are shown. x The band structure in the ′ direction thus shows k f And therefore k c Wide tunability. Due to k f As f grows, it becomes smaller, therefore k c =π / a x -k f =π / a x Growth. In other words, by stretching the lattice by a distance δ in the y-direction, where δ is greater than 0 and less than a. y / 2 (increases the size in actual space), angular growth of the flat band pattern (increases the size in reciprocal space).

[0064] like Figure 6AAs shown, an embodiment of the optical combiner 100 of this disclosure includes a first structured layer 102 of a material having a first refractive index. The structured layer 102 includes a surface 103 having a periodically arranged array 105 of generally cylindrical recesses 106. A second layer 120 of a material having a second refractive index covers the surface 103 and at least substantially occupies the volume of each of the recesses 106. The difference between the first and second refractive indices, measured at 587.5 nm, is less than about 1.5.

[0065] The light incident on structure 106 can be polarized or unpolarized. For example, the input signal 115 incident on structure 106 can be transversely magnetically (TM) polarized (p-polarized) light or transversely electrically (TE) polarized (s-polarized) light. The input signal 115 is incident on structure 106 of the first structured layer 102 at an incident elevation angle θ greater than about 20° (±1°), greater than about 30°, greater than about 40°, or greater than about 50°. In some examples, the incident elevation angle θ is about 40° to about 80°, about 50° to about 70°, about 50° to about 60°, about 55° to about 60°, or about 58°.

[0066] In some examples, the input signal 115 may be a polarized narrowband signal, such as a signal having visible wavelengths of red, green, and blue (RGB). In some examples, the polarized RGB input signal includes a red band with wavelengths from about 620 nm to about 720 nm, a green band with wavelengths from about 500 nm to about 570 nm, and a blue band with wavelengths from about 460 nm to about 500 nm.

[0067] In some examples, Figure 6A Different narrowband reflection peaks of the output signal of the optical combiner 100 can be configured to provide an average reflection greater than about 50%, or greater than about 70%, or greater than about 80%, or greater than about 90%. The optical combiner 100 provides the average reflection peak in the output signal within a range of ±10°, ±5°, or ±3° of a selected elevation angle signal θ. In some examples, the optical combiner 100 can produce reflection peaks within a wavelength range of about 400 nm to about 700 nm, or about 700 nm to about 2 micrometers (μm).

[0068] In some examples, the optical combiner 100 can be positioned at an azimuth angle of about -5° to about 5°, or about -3° to about 3°. ( Figure 6A It provides the reflection peak in the output signal within the range of ).

[0069] To provide good optical performance in applications such as HUDs, a suitable optical combiner 100 should have good performance at both elevation angle θ and azimuth angle θ. Both provide the desired output signal reflection peak within their expected range. However, due to the azimuth angle... Centered on 0°, the elevation angle θ can be more sensitive to angular offset in some examples, and therefore the discussion of this disclosure focuses on the elevation angle θ. In this disclosure, unless the reference to an angle specifically indicates that the angle is an azimuth or angle... Otherwise, the angle referred to is the angle of elevation θ.

[0070] In some examples, the optical combiner 100 has less than about 1% haze for transmitted light in the wavelength range of unpolarized light in the wavelength range of about 400 nm to about 700 nm that is incident on a structured surface at any angle of incidence.

[0071] In another example, for unpolarized light in the wavelength range of about 400 nm to about 700 nm incident on a structured surface at any incident angle, the optical combiner 100 has a reflection of less than about 10%.

[0072] In some examples, the first structured layer 102 is a material with a refractive index less than about 3. In one example, the first structured layer 102 includes, but is not limited to, materials such as titanium dioxide (TiO2) having a refractive index n = 2.4. Other suitable materials for the first structured layer 102 include acrylate resins filled with zirconium oxide or titanium dioxide, which can be deposited, for example, by coating; and metal oxides, nitrides, and oxynitrides, including oxides, nitrides, and oxynitrides of Si, Ti, Zr, Hf, Nb, Ta, or Ce, which can be vapor-deposited. Since silicon is a metalloid, silicon oxide, silicon nitride, and silicon oxynitride are considered to be metal oxides, metal nitrides, and metal oxynitrides, respectively. In some cases, titanium dioxide (TiO2) may be preferred for optical applications involving visible light.

[0073] In some examples, the thickness of the first structured layer 102 is less than about 500 nm, or less than about 200 nm, or less than about 180 nm, or less than about 120 nm.

[0074] In some examples, the second layer 120 may be a polymeric material having a refractive index selected to provide a refractive index difference of less than about 1.5. Suitable examples include, but are not limited to, poly(methyl methacrylate) (PMMA), polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyester, polyimide, and mixtures and combinations thereof.

[0075] In some examples, the second layer 120 of the structure 106 covering the first structured layer 102 may be a material with a refractive index of less than 3, such as TiO2 or any other material listed above, and the first structured layer 102 may be a polymeric material having a refractive index selected to provide a refractive index difference of less than about 1.5.

[0076] In some embodiments, the first structured layer 102, the second layer 120, or both may reside on or between one or more optional support layers 104. In some examples, which are not intended to be limiting, the optional support layer 104 may be made of any suitable optical material, including glass, polymeric materials such as acrylates, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), cyclic olefin copolymers (COP), polycarbonate (PC), and multilayer polymeric optical films. The support layer 104 may comprise one or more layers of the same or different materials.

[0077] The periodic arrangement of structures 105 in the first structured layer 102 can vary widely depending on the intended application of the optical combiner, and structures 106 can have any shape, size, and spacing capable of separating the input light 115 into selected component wavelengths. Figure 6A In one example, the periodic arrangement in the first structured layer 102 includes a lattice 105 of regularly repeating columnar recesses 106.

[0078] like Figures 6B to 6C As shown in detail, the lattice 105 of the recess 106 comprises a hexagonal cell arrangement perturbed to form rectangular cells. The perturbed recessed lattice in surface 103 possesses a lattice constant α in the second (y) direction in the plane of the undisturbed recessed lattice. y The lattice constant a in the first (x) direction in the plane of the undisturbed recessed lattice x The ratio is r(3). 1 / 2 , where the size factor r is approximately 0.8 to approximately 1.2. In some examples, a x and a y Less than approximately 500 nm, or a x Smaller than approximately 300 nm and a y Less than about 400 nm. The perturbed lattice 105 includes columnar recesses 106 arranged in rows along a first (x) direction in the plane of surface 103, and wherein every other row of columnar recesses is laterally offset in the plane of surface 103 in a second (y) direction by a distance δ of about 1 nm to about 100 nm, or about 50 nm to about 75 nm.

[0079] In some exemplary embodiments, the lateral distance δ is from about 1 nm to about 100 nm, and a x and ay Less than about 500 nm, or δ is about 50 nm to about 75 nm, where a x Less than approximately 300 nm, and where a y Less than approximately 400nm.

[0080] In various exemplary embodiments, the diameter D of the cylindrical recess 106 is less than about 200 nm or less than 150 nm.

[0081] exist Figures 7A to 7B In another embodiment shown, Figure 6A The periodic arrangement in the folded metasurface 103 of the first structured layer 102 includes a lattice 125 of regularly repeating rectangular recesses 126. The lattice 125 of the recesses 126 comprises an arrangement of hexagonal cells perturbed to form rectangular cells, and the perturbed lattice of the rectangular recesses in surface 103 has a lattice constant α in the second (y) direction in the plane of the undisturbed recess lattice. y and the lattice constant a in the first (x) direction in the plane of the undisturbed recessed lattice. x In some examples, a y and a x Each is less than approximately 300 nm, or a y =277nm and a x =240nm.

[0082] In some examples, the rectangular recess 126 has a length of about 100 nm to 500 nm and a width of about 20 nm to 50 nm, or a length of about 100 nm to 200 nm and a width of about 30 nm to about 50 nm.

[0083] like Figure 7A As shown, in lattice 125, every other row is offset by a distance δ = LW, where L = the length of the rectangular recess and W = the width of the rectangular recess, where δ is approximately 1 nm to approximately 100 nm or approximately 50 nm to approximately 75 nm. Compared to the device in Figure 6, lattice 125 is now doubled along the x-direction and now combines two sets of rectangular recesses 126. In one row, the rectangular recesses 126 are oriented at angles α1 and α1+90°, alternating every other recess. In adjacent rows, the slits of the recesses 126 are oriented at angles α2 and α2+90°, where α1 ≠ α2. In some examples, α1 = 45° and α2 = 0°.

[0084] exist Figure 7B The diagram shows the corresponding region folding, and again shows the folding of the state away from the Γ point at the edge of the unperturbed FBZ to the non-zero quasi-momentum k. c .

[0085] In another example, the structured layer includes a cascaded arrangement in which multiple periodic structures are stacked on top of each other, such that incident light interacts continuously with the periodic structures. For example, a first periodic structure in the stack may be configured to support dual resonance, and a second periodic structure in the stack may be configured to support single resonance. For example, a first structured surface including a first recessed arrangement configured to support dual resonance may be stacked at a predetermined distance above a second recessed arrangement configured to support single resonance.

[0086] like Figure 8A As schematically shown, the optical combiner 150 includes a first structured layer 152 having a first surface 153, the first surface including an arrangement of periodic structures 155 configured to support dual resonances such as green-blue (GB). A second structured layer 162 includes a second surface 163 having a second arrangement of periodic structures 165, the second arrangement being configured to support single resonances such as red (R).

[0087] The structures in the first structured layer 152 and the second structured layer 162 are regular repeating lattices of columnar recesses 156 and 166, similar to... Figures 6B to 6C Those shown. Lattices 155 and 165 comprise an arrangement of hexagonal cells perturbed to form rectangular cells. The perturbed recessed lattices in surfaces 153 and 163 possess a lattice constant α in the second (y) direction in the plane of the undisturbed recessed lattice. y The lattice constant a in the first (x) direction in the plane of the undisturbed recessed lattice x The ratio is r(3). 1 / 2 , where r is approximately 0.8 to approximately 1.2. In some examples, a x and a y Less than approximately 500 nm, or a x Smaller than approximately 300 nm and a y Less than approximately 400nm.

[0088] The perturbed lattice 155, 165 includes columnar recesses 106 arranged in rows along a first (x) direction in the plane of surfaces 153, 163, wherein every other row of columnar recesses is laterally offset by a distance δ in a second (y) direction of about 1 nm to about 100 nm, or about 50 nm to about 75 nm.

[0089] In some exemplary embodiments, the lateral distance δ is from about 1 nm to about 100 nm, and a x and a y Less than about 500 nm, or δ is about 50 nm to about 75 nm, where a x Less than approximately 300 nm, and where a y Less than approximately 400nm.

[0090] In various exemplary embodiments, the diameter D of the cylindrical recess 106 is less than about 200 nm or less than 150 nm.

[0091] In an example that is not intended to be limiting, in order to form a dual-resonant BG filter, the first structured layer 152 includes columnar recesses 156 arranged in rows, such that a x =187.5nm, a y =315nm, D x =125nm, D y =155nm, δ=25nm, and the layer thickness is 208nm. To form a single resonant R-filter, the second structured layer 162 further includes rows of columnar recesses 166, such that a x =250nm, a y =420nm, D x =D y =180nm, δ=60nm, and the layer thickness is 100nm. Layers 152 and 162 are in the encapsulation layer ( Figure 8A Positioned at a distance d of 500 nm (not shown in the image) s The separation allows the encapsulation material to essentially occupy the volume of the cylindrical recesses 156 and 166. The refractive index difference between the first structured layer 152, the second structured layer 162, and the encapsulation layer is less than about 1.5.

[0092] As mentioned above, in contrast to Figures 6A to 6C As discussed in the embodiments, layers 152 and 162 may be made of a material with a refractive index less than about 3 (such as TiO2). The encapsulation layer may be a polymer material whose refractive index is selected to provide a refractive index difference of less than about 1.5 relative to the refractive index of layers 152 and 162. In some examples, encapsulation layer 350 may be a dielectric material such as TiO2, and layers 152 and 162 may be made of a polymer material whose refractive index is selected to provide a refractive index difference of less than about 1.5 between the dielectric material and the polymer material.

[0093] Now for reference Figure 8B The curve, representing the 0th order reflectance spectrum within the range of oblique incident elevation angle θ = 55°-61°, is for... Figure 8A The first structured layer 152 was plotted, and different peaks at 457nm and 530nm were shown. Figure 8C Showing the target Figure 8A The second structured layer 162 plots the 0th order reflectance spectrum in the range of tilted incident elevation angle θ = 55°-61°, and shows a peak at 630 nm.

[0094] like Figure 8DThe graph shows the reflectance of TM-polarized light under oblique incidence. Figure 8A The optical combiner 150 includes both structured layers 152 and 162, which provide an output signal with three resonant peaks. Figure 8E and Figure 8F The zero-order reflection and transmission spectra of the optical combiner 150 are shown in the figure.

[0095] The resonant frequency of the reflected output signal can be tuned by changing the fundamental parameters of the structure forming the metasurface (such as height and duty cycle). By changing the symmetry to reduce the magnitude of the perturbation δ, the linewidth of the resulting resonant state follows Q∝1 / δ. 2 For example, in the devices of Figures 5 and 6, δ is implemented as the lateral offset of the circular aperture, while in the device of Figure 7, it is δ = LW. The operating angle of the device is then determined by the ratio f = a of the undisturbed lattice size. y / a x The controlled folding quasi-momentum k c The polarization state can be arbitrarily changed by adding additional degrees of freedom, including exhibiting full circular dichroism.

[0096] The zero- and first-order dispersion of band-edge modes is particularly suitable for applications requiring narrow-band reflection characteristics over large incident angles. Because band-edge modes originate from mode mixing (open bandgap) due to the periodicity of the device (disruption of continuous translational symmetry), they possess well-defined momentum properties determined by the symmetry of the periodic device (discrete translational symmetry). Perturbing a high-symmetry lattice can be used to select the momentum of the free space coupled to this mode. While band-edge modes can exist at arbitrary angles in conventional methods by modifying the mode mixing of several modes, in the device of this disclosure, this functionality is achieved in a symmetry-protected manner. That is, for a wide parameter range, flat band modes will exist near the desired operating angle without requiring any precise alignment of several unrelated modes. Maximum Bragg local modes (e.g., K points of a hexagonal lattice) can be accessed at any operating angle for a given refractive index contrast system.

[0097] The symmetry-based perturbation method employed in this disclosure is also useful relative to broadband features: only narrowband features exist in the visible spectral region, thus making the response to most visible light transparent and undistorted. In some examples, in addition to HUDs, the optical combiners of this disclosure can also be used in applications such as AR displays, where high clarity and visibility of external information are required. The metasurfaces of this disclosure provide narrow spectral features that produce enhanced reflections over a wide angular range, which may be desirable for superimposing artificial information in projected AR displays. While transversely magnetic (TM or p-polarized) light is of particular interest in most cases (making the Brewster angle usable to eliminate double images originating from reflections from the air-glass interface), the nonlocal metasurfaces of this disclosure can control the polarization states of these regions of the folded QBIC structure, thus providing additional flexibility in optical design.

[0098] The enhanced light-matter interactions of these long-term states enable the optical combiners of this disclosure to be used in a wide variety of applications. For example, thermal emission modification using edged QBICs (present under normal incidence) can be used to generate compact light sources, and the method of this invention can enhance these concepts by enabling direct modification of anomalous edged modes with different polarization states depending on the light direction. The enhanced light-matter interactions provided by q-BICs can also be used to generate active devices tunable by electro-optic or thermal methods, where the localization of edged modes enables more compact devices. Similarly, applications such as biosensing and nonlinear optics benefit from long-term states and localization. The optical combiners of this disclosure are scalable to any selected linewidth, anomalous operating angle, and polarization.

[0099] The zone-folded metasurface disclosed herein possesses scalar and vector properties with symmetry control. The perturbation method used to form the metasurface introduces narrowband characteristics with on-demand symmetry control over linewidth, operating angle, and resonant polarization state. In some examples, the resulting device provides enhanced reflection with increased angular tolerance beyond conventional designs, while maintaining a largely undistorted and highly transmissive broadband response. This combination of features in the periodic structure is uniquely suited as a scalable solution for AR applications (compatible with roll-to-roll manufacturing).

[0100] Now refer to the drawing that is not to scale. Figure 9A The schematic diagram is shown above. In another aspect, this disclosure relates to a method 200 for manufacturing the optical combiner shown above. In method 200, in step 202, a metal (such as chromium) layer 208 is applied to a glass layer 204 on which a TiO2 layer 206 is applied by electron beam evaporation. An electron beam resist layer 210 is spin-coated onto the Cr layer 208.

[0101] In step 212, the electron beam resist layer 210 is exposed to an electron beam in a selected area to form a pattern 214 suitable for creating a folded metasurface. In step 216, after development, the pattern 214 is transferred to the Cr layer 208 via a dry etching process. In step 216, the pattern 214 is transferred to the TiO2 layer 206 via dry etching to form a recess 224, and any remaining portion of the Cr layer 208 is removed via a wet etching process.

[0102] As shown in step 220, the polymer layer 230 is then spin-coated onto the TiO2 layer 206, and the polymer layer fills the depression 224 therein.

[0103] exist Figure 9B In another embodiment shown, method 250 for manufacturing an optical combiner includes step 252 of providing a structured polymer film 254, the structured polymer film including a pattern 256 suitable for generating recesses 258 of a folded metasurface. The polymer film 254 can be structured using a wide variety of techniques for forming the recesses 258, including etching, laser drilling, micro-replication by metal tools, and combinations thereof.

[0104] As shown in step 260, the structured polymer film 254 may be coated with an encapsulation layer 270 of a dielectric material (such as TiO2) such that the dielectric material occupies the recess 258.

[0105] One or more optional support layers may be added to the dielectric layer 270 or the polymer film 254. Figure 9B (Not shown in the image).

[0106] like Figure 10 As shown, in another aspect, this disclosure relates to an optical combiner film 300, which includes one or more optional support layers 304, a structured layer 302 with a pattern 310 having recesses 312, and a cover or encapsulation layer 320. In some examples, the combiner film 300 can be manufactured at a relatively low cost using a roll-to-roll process and can be easily manufactured or cut into large formats for use in optical displays, vehicle windshields, etc.

[0107] Refer again Figure 10 In some examples, the optical combiner film 300 may be laminated between glass layers 350A and 350B to form a windshield configuration 360 for use in vehicles, aircraft, etc. In some examples, the optical combiner film 300 may be laminated to either of the glass layers 350A and 350B, or even to the inner surface of the windshield near the vehicle or aircraft operator.

[0108] like Figure 1As schematically shown, the windshield structure 360 ​​can be integrated into a head-up display (HUD) system used in vehicles, aircraft, etc., or can be used as a component of the optical system in an AR device.

[0109] The device of this disclosure will now be further described in the following non-limiting embodiments.

[0110] Example

[0111] Example 1

[0112] pass Figure 9A The diagram illustrates a standard top-down photolithography process for fabricating gratings.

[0113] A TiO2 layer was deposited on a 1 mm thick quartz substrate and etched down to the desired thickness. A 70 nm thick chromium layer was deposited via electron beam evaporation, and a 300 nm thick electron beam resist layer (ZEP 520-A, available from Zeon Corp., Marunouchi, JP) was spin-coated onto the top of the sample. A photonic crystal pattern was written using an electron beam tool (Elionix 100keV, available from Elionix, Inc., Tokyo, JP). After development, the pattern was transferred to the chromium layer via a Cl2-O2 dry etching process performed in an ICP machine (Oxford PlasmaPro System100Cobra, available from Oxford Instruments, Bristol, UK). After removing the ZEP mask, the pattern was further transferred to the titanium dioxide layer via a CF4-Ar-O2 dry etching process performed in the same ICP machine. The residual chromium mask was then removed via wet etching. To embed the titanium dioxide metasurface into a glassy (n=1.5) dielectric environment, a thin layer of polymethyl methacrylate (PMMA) 11 (MicroChem, Newton, Massachusetts) was spin-coated onto the top of the sample. A denser version of the same polymer (PMMAA11, MiCroChem) was then drop-cast onto the top of the sample and used as an adhesive layer to bond a 1 mm thick microscope coverslip. The in-plane dimensions of the fabricated metasurface were approximately 700 to approximately 1000 micrometers.

[0114] By placing the sample in such Figures 11A to 11B The motor-controlled rotating stage shown is used to acquire angle-dependent transmission and reflection spectra, which allows for precise control of angle θ. For transmission measurements ( Figure 11AA broadband white light beam is linearly polarized and weakly focused onto the sample (focal length f = 10 cm) to obtain an excitation spot with a diameter of approximately 300 μm. This excitation configuration is chosen as a compromise to ensure that the beam spot is smaller than the grating cross-section even for large angles θ, while minimizing the excitation angular spread.

[0115] A beam is collected from the other side of the sample using the same lens and guided to a CCD camera (for alignment purposes) or a fiber-coupled spectrometer. For each angle, the beam is acquired through a grating S. grat The lamp spectrum transmitted through (λ,θ) is obtained and passed through a bare glass substrate S0(λ,θ), and the transmission spectrum is calculated. This procedure appropriately accounts for the lateral beam deflection introduced at a large angle by the thick glass substrate, which can alter the collection efficiency. Due to the normalization used, T(λ,θ) does not include the effects of the air / glass interface and the glass / air interface. To correct for this, the thick glass plate T... 玻璃 (λ,θ) calculates the angle-dependent incoherent transmission spectrum, which is used to calculate the absolute transmission T of the sample. abs (λ,θ)≡T(λ,θ)×T 玻璃 (λ,θ).

[0116] For reflection measurement ( Figure 11B A linearly polarized tunable laser (SuperK Fianium, available from NKT Photonics, Boston, MA) was used as the source. A portion of the laser was extracted via a beam splitter and guided to a power meter (P1) for power correction before being focused onto the sample. The beam reflected by the grating was collimated by a lens and measured by a second power meter (P2). The collecting lens and power meter P2 were both placed on the second rotating stage at an angle set to 180°–2θ to measure specular reflection. The absolute reflection spectrum was then obtained by scanning the excitation wavelength and recording the power measured by P1 and P2.

[0117] above Figures 6A to 6C The equipment (which includes a) x =231nm, a y =386nm, D=143nm, and δ=66nm), p-polarized transmission spectrum (for simulated response) Figure 6D and for measurement response Figure 6F The expected characteristics are shown: the upper band (i.e., the longest wavelength mode) is flattened at an incident angle θ of approximately 58°, due to the avoidance of the crossover between this band and the lower band (see also...). Figure 6D (The right inset is for magnification). Therefore, the transmission drop associated with this band (at λ of approximately 627 nm) is almost undispersed within the angular range of interest (θ = 58° ± 3°), as... Figure 6H As shown.

[0118] s-polarized transmission spectroscopy (for simulated response) Figure 6E and for measurement response Figure 6G Similar characteristics were observed, with different bands (typically narrower than in the p-polarized case) and avoidance of crossovers, although at different angles. While not wishing to be bound by any theory, the simulation and measurement of transmission (especially for s-polarized at large angles) showed similar characteristics. Figure 6E , Figure 6G The difference in absolute values ​​of (see) is likely due to the neglect of the presence of two air / glass interfaces in the simulation. As expected, for s-polarized excitation, the measured transmission decreases at large angles due to the large reflections at the two glass / air interfaces. For p-polarized excitation, this effect is less significant because reflections at the air / glass interfaces are zero at the Brewster angle (θ = approximately 58°).

[0119] As mentioned above, a key quality factor for ensuring these devices are usable for augmented reality (AR) applications is that, in addition to their operating wavelength, they are primarily transmissive to unpolarized broadband signals in the visible range. To quantify this, calculations are performed... Figures 6F to 6G The average value between two datasets (used to simulate unpolarized beams) was calculated, and then further averaged across wavelengths in the visible range. The resulting curve ( Figure 6I Curve B) shows that the average unpolarized transmission is almost 80% under normal incident conditions, while it drops to about 60% at an operating elevation angle θ = 58°. The slow decrease in average transmission with increasing θ is mainly due to the reduction in the transmission of the TE component. For comparison, Figure 6I Curve R in the figure shows the average unpolarized transmission of the thick glass plate.

[0120] To confirm that the decrease in transmission is due to large reflections and to quantify the loss, the above-mentioned... Figures 11A to 11B The technique described in the discussion is used to measure the reflectance spectrum at a selected angle. Figure 6J In this study, the reflection spectrum at θ = 58° (line B) is compared with the transmission spectrum at the same angle (line R). Three transmission drops in the 500 nm to 700 nm range are accompanied by corresponding reflection peaks with nearly equal magnitudes. Similarly, while not wishing to be bound by any theory, the small difference between the center wavelengths of the transmission drops and transmission peaks is believed to be due to minor spectral detuning between the different instruments used for reflection and transmission measurements. For the peak of interest (λ = approximately 627 nm), a 6% transmission drop is accompanied by an 83% reflection peak, indicating the presence of approximately 11% loss of resonance. In some examples, this loss can be attributed to manufacturing defects (i.e., roughness) and residues from the metal mask used in the fabrication.

[0121] Example 2

[0122] In another embodiment, a preparation was made Figures 7A to 7B The device contains four rectangular apertures, each 45 × 110 nm in size, rotated at angles α1, α1 + 90°, α2, and α2 + 90°. The plate has a height H = 180 nm and a lattice constant of α. x =240nm and a y =277nm.

[0123] The expected intrinsic polarization is as follows:

[0124]

[0125] Where c1 and c2 depend on how the dimensions W×L of the rectangle differ from those of the square (i.e., c1∝L1-W1 and c2∝L2-W2). Factor i = (-1) 1 / 2 From the two rows, a quarter-cycle offset in the x-direction, and k x The momentum is in-plane and therefore positive when light is incident through transverse momentum pointing in the +x direction, and negative when light is incident through transverse momentum pointing in the -x direction. Linear intrinsic polarization φ is expected when α1 = α2. eig ≈α1, similar to Figures 2 to 3 The response of the device in the diagram. However, in this case, elliptic dichroism can be observed when α1≠α2.

[0126] Figures 7C to 7D The reflectance of RCP and LCP light in the blue region of the devices with α1 = 45° and α2 = 0° are shown respectively.

Claims

1. An optical combiner, the optical combiner comprising: The first layer includes a periodic two-dimensional arrangement of structures arranged to support resonance for an input signal of a target wavelength, wherein the structures have a first refractive index. A second layer covers the structure on top of the first layer, wherein the second layer comprises a second material having a second refractive index, and wherein the difference between the first refractive index and the second refractive index measured at 587.5 nm is less than 1.5; and The structure comprises a regularly repeating lattice with perturbed hexagonal cells, wherein the periodic two-dimensional arrangement of the structure is configured such that the optical combiner produces an output signal including a reflection peak for an input signal incident on the first layer from air at an elevation angle greater than 20°, wherein the reflection peak has an average reflectivity greater than 50% within ±5° of the elevation angle.

2. The optical combiner according to claim 1, wherein the elevation angle is greater than 20° and less than or equal to 70°.

3. The optical combiner according to claim 1, wherein the input signal is TM polarized.

4. The optical combiner of claim 3, wherein the input signal comprises red, blue, and green (RGB) wavelengths of visible light.

5. The optical combiner of claim 1, wherein the output signal includes the reflection peak in the wavelength range of 400 nm to 2 micrometers.

6. The optical combiner of claim 1, wherein the optical combiner generates the output signal in an azimuth angle range of -5° to 5° in a plane perpendicular to the incident plane of the input signal.

7. The optical combiner according to claim 1, wherein the arrangement of the structure is perturbed.

8. The optical combiner of claim 1, wherein the structure comprises a quasi-constrained state structure in a continuum.

9. The optical combiner of claim 1, wherein the second material occupies at least a portion of the volume of each recess.

10. The optical combiner of claim 9, wherein the perturbed recessed lattice has rectangular cells.

11. The optical combiner of claim 10, wherein the perturbed recessed lattice comprises columnar recesses arranged in rows along a first direction in the plane of the first layer, and wherein every other row of the columnar recesses is laterally offset by a distance δ in the plane of the first layer and in a second direction perpendicular to the first direction.

12. The optical combiner of claim 11, wherein the perturbed recessed lattice has a lattice constant α in a second direction in the plane of the undisturbed recessed lattice. y The lattice constant a in the first direction in the plane of the undisturbed recessed lattice x The ratio.

13. The optical combiner of claim 11, wherein the perturbed recessed lattice comprises rectangular recesses extending into the plane of the first layer and arranged in rows along a first direction in the plane of the first layer, wherein every other row is laterally offset by a distance δ = LW, where L = length of the rectangular recess and W = width of the rectangular recess.

14. The optical combiner of claim 13, wherein the alternating rectangular recesses in the first row of the row pair are oriented at angles α1 and α1+90°, and the alternating rectangular recesses in the second row of the row pair adjacent to the first row are oriented at angles α2 and α2+90°, wherein α1≠α2.

15. The optical assemblies of claim 1, wherein the first layer comprises a polymer material with a refractive index of 1.2 to 1.55, and the second layer comprises TiO2.

16. An optical combiner film, the film comprising: A structured layer covered by a capping layer, wherein the structured layer comprises a periodic lattice with regularly repeating recesses, wherein the recessed lattice has perturbed hexagonal cell units, and wherein the difference between the refractive index of the structured layer and the refractive index of the capping layer, measured at 587.5 nm, is less than 1.

5. The periodic lattice is configured such that the optical combiner film produces an output signal including a reflection peak for an input signal incident on the structured layer from air at an elevation angle greater than 20°, wherein the reflection peak has an average reflectivity greater than 50% within ±5° of the elevation angle.

17. The optical combiner film of claim 16, wherein the structured layer comprises a polymer material with a refractive index of 1.2 to 1.55, and the capping layer comprises TiO2.

18. A method for manufacturing an optical combiner film, the method comprising: A first layer is formed on a polymer support film, wherein the first layer comprises a periodic arrangement of recesses and a perturbed arrangement of hexagonal cells, and wherein the first layer comprises a material having a first refractive index. A cover layer is applied on the first layer, wherein the cover layer comprises a material having a second refractive index, and wherein the difference between the first refractive index and the second refractive index measured at 587.5 nm is less than 1.5; The structure in the first layer is configured such that the optical combiner film produces an output signal including a reflection peak for an input signal incident on the first layer from air at an elevation angle greater than 20°, wherein the reflection peak has an average reflectivity greater than 50% within ±5° of the elevation angle.

19. The method of claim 18, further comprising attaching the optical combiner film to a glass sheet to form a windshield laminate.

Images