• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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    • 专利摘要:
    The invention relates to a metasurface lens using a planar network of elementary resonators, each elementary resonator having the shape of a cross whose arms are of unequal lengths. The phase shift applied by an elementary resonator is a function of its orientation in the plane of the lens, the orientation of the different elementary resonators is determined according to the shape of the desired wavefront. Such a lens has a substantially uniform distribution of the transmission coefficient and a low chromatic aberration. In addition, it has a very good spectral selectivity.
    公开号:FR3061962A1
    申请号:FR1750289
    申请日:2017-01-13
    公开日:2018-07-20
    发明作者:Giacomo BADANO；Johan Rothman
    申请人:Commissariat a lEnergie Atomique CEA；Commissariat a lEnergie Atomique et aux Energies Alternatives CEA；
    IPC主号:
    专利说明:

    @ Holder (s): COMMISSION FOR ATOMIC ENERGY AND ALTERNATIVE ENERGIES Public establishment.
    O Extension request (s):
    ® Agent (s): BREVALEX.
    ® LENS WITH FOCUSING METASURFACE AND LOW CHROMATIC ABERRATION.
    FR 3 061 962 - A1 (57) The invention relates to a metasurface lens using a planar network of elementary resonators, each elementary resonator having the shape of a cross whose arms are of unequal lengths. The phase shift applied by an elementary resonator is a function of its orientation in the plane of the lens, the orientation of the different elementary resonators is determined as a function of the shape of the desired wavefront. Such a lens has a substantially uniform distribution of the transmission coefficient and a low chromatic aberration. In addition, it has very good spectral selectivity.

    ι
    LENS WITH FOCUSING METASURFACE AND LOW CHROMATIC ABERRATION
    DESCRIPTION
    TECHNICAL AREA
    The object of the present invention relates to flat lenses with metasurface, in particular with focusing metasurface. The present invention can in particular be applied to spectral sorting.
    PRIOR STATE OF THE ART
    Conventional optical lenses use the refractive properties of the materials that compose them to modify the wave fronts and control the optical paths of the beams that pass through them.
    These optical lenses are generally thick, especially for short focal distances. To obtain smaller thicknesses, it is well known to use Fresnel lenses. In practice, Fresnel lenses are produced by numerous levels of lithography so as to discretize the variation in dielectric thickness necessary to obtain the desired shape of the wavefront at the output. In addition, Fresnel lenses do not exhibit spectral selectivity.
    Metasurfaces lenses allow a continuous phase variation with good spectral selectivity while having a low thickness. These metasurface lenses generally use networks of elementary optical resonators (also called optical antennas) with a density substantially lower than the incident wavelength of interest. The shape, size and orientation of these optical antennas are chosen to obtain the desired wavefront shape.
    In general, it is known to make flat lenses with metasurface. A structured surface is called metasurface to create a network of resonators whose dimensions and network pitch are less than the wavelength. Sub wavelength resonators are generally obtained by lithography from a dielectric or metallic layer deposited on a substrate. The phase and amplitude of the light wave re-emitted by each elementary sub-wavelength resonator depend on its geometry, its orientation with respect to the polarization of the incident wave and the materials which constitute it. This wave can be considered as a spherical wave affected by a phase delay with respect to the incident wave.
    A general introduction to metasurface lenses can be found in the article by N. Yu etal, entitled "Fiat optics with designer metasurfaces" published in Nature Materials, Vol. 13, Feb. 2014, pp. 139-150.
    An example of a converging metasurface lens was proposed in the article by X. M. Goh et al. entitled “Plasmonic lenses for wavefront control applications using twodimensional nanometric cross-shaped aperture arrays” published in J. Opt. Soc. Am. B, Vol. 28, No. 3, March 2011, pp. 547-553. This lens is formed by a periodic network of crosses of variable size (decreasing size from the center towards the periphery for a converging lens and increasing from the center towards the periphery for a diverging lens). However, if this lens structure is simple, it has a major drawback in that it is not possible to independently control the phase and the law of transmission in wavelength (in particular the transmission coefficient in wave length). This results in apodization of the pupil at a determined wavelength. In addition, this type of lens has a strong chromatic aberration. In other words, the focal length of this type of lens varies significantly with the wavelength. Finally, this type of lens has a low spectral selectivity.
    The object of the present invention is therefore to provide metasurface lenses having only a low chromatic aberration in a predetermined spectral band, while guaranteeing a uniform distribution of the transmission coefficient for a given wavelength, as well as '' better spectral selectivity.
    STATEMENT OF THE INVENTION
    The present invention is defined by a metasurface lens intended to receive an incident wave of given wavelength, comprising at least a first network of resonators, located in a plane of the lens, said resonators of the first network being crosses of shapes identical, each cross comprising at least a first arm, said long arm, extending along a first axis and a second arm, said short arm, of length strictly less than the long arm and extending along a second axis, substantially orthogonal to the first axis, each cross phase shifting the incident wave by introducing its own phase shift depending on the orientation of the cross relative to a reference direction in the plane of the lens.
    The length of the long arm is typically 5% to 10% greater than the length of the short arm.
    Advantageously, the lengths of the long and short arms are chosen so that the difference between the resonance frequency of the long arm and the resonance frequency of the short arm is less than the width at half height of the spectral response in transmission. of each of said arms.
    Preferably, the crosses are produced by recesses within a metal layer, the metal layer being deposited on a first dielectric layer transparent to said given wavelength.
    In addition, these recesses can be filled with a material with an optical index higher than the optical index of the first dielectric layer.
    The first dielectric layer can itself be deposited on a semiconductor substrate transparent to said given wavelength, the optical index of the substrate being greater than the index of the first dielectric layer.
    In addition, a second dielectric layer can be deposited on the metal layer, said second dielectric layer being made of the same material as
    J the first dielectric layer and being of thickness - where λ is said given wavelength Ίη and M is the index of the first and second dielectric layers.
    According to a first embodiment, the metasurface lens is a converging lens, of focal length f and the orientation of a cross whose center is located at a point p. of coordinates ( A ,. vj in a coordinate system (O, x, y) in the plane of the lens is chosen so as to generate its own phase shift φ. =
    Ί-πη 0 λ
    with
    where λ is said given wavelength and n ° is the index of the output medium of the lens.
    According to a second embodiment, the metasurface lens is a converging lens, of focal length f and the orientation of a cross whose center is located at a point p. of coordinates ( x , y ) in a coordinate system (O, x, y) in the plane of the lens is chosen so as to generate its own phase shift φ. = φ. mod —- with
    Φ. =
    Ί-πη 0 λ (f- l x î + yf +
    where n o is the index of the exit medium of the lens, a third dielectric layer of thickness - being deposited only above the 2/7 crosses for which - <| ^ | <π
    According to a variant, the orientation of the crosses can take only a finite set of discrete angular values.
    The first network can be chosen periodically.
    According to a variant of the first embodiment, the metasurface lens comprises a second network of resonators located in the plane of the lens, the resonators of the second network being crosses of identical shape, each cross of the second network being further located in a cross section of size of a cross of the first network, the crosses of the second network being of size smaller than that of the crosses of the first network, each cross of the second network also comprising a long arm and a short arm, each cross of the second network dephasing the incident wave by its own phase shift depending on its orientation, within the second plane of the lens, relative to said reference direction.
    According to an example of application, the incident wave comprises a first spectral component at a first wavelength 2 1 and a second spectral component at a second wavelength y. The metasurface lens can be a converging lens, focal length f, the orientation of a cross of the first network whose center is located at a point p. of coordinates ( x ., y .) in a coordinate system (O, x, y) of the plane of the lens being chosen so as to generate a proper phase shift Æ., · = (/ -7 (V “NΓ + (V - ΤιΓ + / 2 j with | ^, | <y where n o is the optical index of the output medium of the lens, at the wavelength 2 1 , and the orientation of a cross of the second grating whose center is located at a point Pj with coordinates in the coordinate system (O, x, y) being chosen so as to generate a proper phase shift where n o is the optical index of the lens's output medium, at the wavelength z 2 .
    BRIEF DESCRIPTION OF THE DRAWINGS
    Other characteristics and advantages of the invention will appear on reading a preferred embodiment of the invention, with reference to the attached figures among which:
    Fig. 1 schematically represents the geometry of a wavelength resonator used in a metasurface lens according to the invention;
    Fig. 2A schematically represents the structure of a metasurface lens according to a first embodiment of the invention;
    Fig. 2B schematically represents the structure of a metasurface lens according to a second embodiment of the invention;
    Figs. 3A-3C schematically represent respectively a first, a second and a third example of a metasurface lens according to the invention;
    Fig. 4 schematically shows an example of a structured dielectric surface used in the second embodiment of the invention;
    Fig. 5 shows the relative variation of the focal length as a function of a relative variation of the incident wavelength, for an example of a metasurface lens according to the invention;
    Fig. 6 schematically shows an arrangement of wavelength resonators for a metasurface lens according to an alternative embodiment of the invention;
    Fig. 7 schematically shows the use of a metasurface lens to perform spectral sorting;
    Fig. 8 schematically represents the use of metasurface lenses for performing four-color imaging.
    Fig. 9 represents the percentage of photons falling on a portion of the focal plane as a function of the wavelength for one of the metasurface lenses of FIG. 8.
    DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS
    The idea underlying the present invention is to produce a metasurface lens from a two-dimensional network of resonators, the resonators being crosses of identical shape, comprising two orthogonal arms of unequal lengths, each cross introducing a phase shift which it is specific according to its orientation with respect to a reference direction. The fact of using crosses of identical shapes but of variable orientation makes it possible to locally adjust the phase shift applied to the incident wave while guaranteeing a substantially uniform distribution of the transmission coefficient in the plane of the lens. In addition, the fact of using cross arms of unequal lengths with a relatively small relative deviation (from 5 to 15%), as we will see later, makes it possible to reduce the chromatic aberrations in the spectral band of interest.
    Fig. 1 schematically represents the geometry of a cross-shaped wave-length resonator with unequal arm lengths, as used in a metasurface lens according to the present invention.
    The sub-wavelength resonator illustrated in FIG. 1 constitutes the elementary pattern of the network used in the metasurface lens. This resonator comprises a first arm, said long arm, 110, extending in a first direction OX and a second arm, said short arm, 120, extending in a second direction OY, substantially orthogonal to the first direction. The short and long arms cut in their respective circles. The relative difference in length between the long and short arms is advantageously between 5 and 15%, preferably between 5% and 10%.
    The angle ψ made by the long arm, that is to say the axis OX, with a reference direction, for example the axis Ox, will conventionally be designated by orientation of the cross (in the Oxy plane). It will be understood that, taking into account its axial symmetry, the orientation of the cross is included in an angular range of width 7 1.
    Fig. 2A schematically represents the structure, seen in section, of a metasurface lens according to a first embodiment of the invention.
    The metasurface lens is produced from a substrate 210, for example a substrate made of semiconductor material such as Si, CdHgTe, GaAs, GaAlAs, etc., transparent for the wavelength of interest. The optical index of the material (at this wavelength) is chosen to be high, for example equal to 3.5. The substrate represents the exit pupil of the lens.
    The substrate, 210, is covered by a first layer of low index dielectric, 220, that is to say with an optical index substantially lower than that of the substrate. Of
    In general, the thickness of the first dielectric layer is chosen to be equal to - where 2 / M is the optical index of the material of the first dielectric layer.
    The thickness of the first dielectric layer is for example from 100 to 200 nm. S1O2 can be used in the wavelength range 2-9 μιτι and ZnS beyond. Below 2 μιτι, we can use SiO x by choosing its stoichiometry, or another oxide such as ΙΊΤΟ for example.
    The subwavelength resonators are produced by means of a metal layer, 230, deposited on the first dielectric layer. The metal layer is 50 to 300nm thick and made of a metal with very good conductivity, such as Cu, Au, Al or Ag. The thickness of the layer is determined according to the desired spectral selectivity of the lens, a thick layer leading to a narrow resonance and therefore a narrow bandwidth, a thin layer leading to a less marked resonance and therefore to a wider bandwidth.
    This metal layer is structured as explained below.
    The resonators are produced by recesses in the metal layer, these recesses having the shape of a cross with unequal arms, as described in relation to FIG. 1. The recesses can then be filled with a dielectric material with an optical index greater than that of the first dielectric layer. For example, one could choose a dielectric material of index 2.2 for a lens intended to operate in the middle infrared. In certain applications, it will be possible to choose a material with a higher index, for example Si with an index equal to 3.5. Conversely, when the lens is intended to operate in the near infrared, the recesses will be left empty, in other words, they will not be filled with a dielectric material.
    In the above examples, the metal layer can be structured by an etching process, for example a focused ion beam or FIB (Focused Ion Beam) etching or else by a deposition process through a mask. In the first variant, a Damascene process can be used to fill the recesses of the crosses with a dielectric material.
    The structured metal layer 230 is advantageously covered with a second dielectric layer, 240, of the same index n as the first layer
    J dielectric and of thickness equal to -. Thus the structured metallic layer is taken in 2/7 sandwich between two dielectric layers of the same (low) index.
    Fig. 2B schematically represents the structure of a metasurface lens according to a second embodiment of the invention.
    The structure of the metasurface lens according to the second embodiment differs from the structure of the first by the presence of a third layer of dielectric, 250, with the same index as the first and second layers of dielectric. This third dielectric layer is structured, unlike the first and second dielectric layers.
    J
    More precisely, as explained below, this layer of thickness - is not present
    2 / î that above certain resonators only to locally apply an additional phase shift of 7Î to the incident wave.
    The sub-wavelength resonators are arranged in the plane of the metasurface lens in a two-dimensional network. This network can be a periodic network, for example a rectangular network, a hexagonal network or even a circular network. The network can alternatively be chosen pseudo-random. Preferably, we will opt for a network allowing to have the greatest number of resonators on the surface of the lens, in other words to obtain the highest filling rate of the entrance pupil (problem known as close packing, well known skilled in the art). We call here the filling ratio:
    where S is the surface of the entrance pupil, N is the number of resonators and (J is the cross section of the elementary resonator.
    The choice of a high filling ratio makes it possible to obtain a high transmission coefficient and a better spatial resolution of the wavefront.
    The respective orientations of the different resonators are chosen so as to generate the desired wavefront.
    More precisely, according to a first embodiment, if one wishes to produce a converging lens with focal length f and if one notes (^, χ) the coordinates of the phase center of an elementary resonator (sub-length of wave) i in the plane of the lens, its orientation ψ . is chosen so as to create a phase shift of:
    ίο (2)
    with φ. |
    Ί-πη 0 λ (/ “Vt + Ζ 2 +
    <-, where λ is the wavelength of the incident wave and η ° is the index of the output medium of the lens, in this case, here, the index of the substrate. It will be noted that the sub-wavelength resonator can only apply a phase shift limited to a phase range of width 7 1. In other words, the lenses according to the first embodiment have a relatively small numerical aperture.
    According to a second embodiment, to produce a focal lens f, the orientation of each elementary resonator is chosen so as to create a phase shift:
    (2-1) with
    Ί-πη 0 λ (/ -® 2 + Z 2 + / 2 ) (2-2)
    As indicated in relation to FIG. 2B, a third thick dielectric layer - is deposited only on top of the resonators for which 2/7
    | ^ | <π This second embodiment makes it possible to cover the entire phase shift range [0.2; r] and therefore to obtain any focal distance.
    In practice, to simplify the production of the metasurface lens, it will be possible to authorize only a finite set of discrete orientations of the elementary resonators.
    Whatever the embodiment, the transmission coefficient (or attenuation coefficient) of the lens is distributed in a substantially uniform manner over the entrance pupil. In fact, the orientation of an elementary resonator, due to its cross structure, has little effect on the transmission coefficient for non-polarized light. Thus, the phenomenon of apodization observed in prior art metasurface lenses is absent here.
    Figs. 3A, 3B and 3C respectively represent a first, a second and a third embodiment of a metasurface lens according to the invention.
    These embodiments relate to a metasurface lens with a square section. The elementary sub-wavelength resonators are formed by cross arms with unequal lengths, as described in relation to FIG. 1. The cross sections of elementary resonators are represented by circles.
    The two-dimensional arrangement of the resonators in the lens of FIG. 3A corresponds to a square network (the generator vectors of the network are directing vectors of the axes Ox and Oy). The two-dimensional arrangement of FIG. 3B corresponds to a hexagonal network (the generator vectors of the network form an angle of 30 ° between them). Finally, that of FIG. 3C corresponds to a circular network, the resonators being arranged in concentric circles. It will be noted that at constant cross section <5, the highest filling rate is obtained here by a hexagonal network. It will also be noted that in the third example, the elementary resonators located at the same distance from the center of the lens all have the same orientation, which is very consistent with the fact that they introduce the same value of phase shift.
    The orientation of the elementary resonators can be obtained by means of a simulation.
    According to a first variant, called semi-analytical variant, this simulation relates to an elementary resonator alone. More precisely, the geometrical shape of the resonator and in particular the relative deviation of the lengths of its arms is fixed beforehand and the phase shift law cp = F (i //) is determined by simulation as a function of the orientation ψ of the resonator with respect to to a reference axis. It is then possible to calculate, from the position (%, ·, y) of any resonator, the phase shift to be applied from expressions (1) or (2-1), (2-2) and d 'deduce the orientation ψ . of the resonator.
    According to a second variant, the simulation is carried out on all of the elementary resonators of the lens. More precisely, the network type and the geometric shape of the elementary resonator are chosen beforehand (in particular the relative difference in the lengths of its arms). We then optimize step by step the orientation of the different crosses to maximize a merit function, for example the intensity of the diffracted wave at the desired focal point or the average of the intensity of the diffracted wave in the focal spot. desired.
    Although the examples given above relate to lenses converging at a focal point, those skilled in the art will understand that it is always possible, from a desired distribution of phase and amplitude in the focal plane, to deduce by Fourier transform reverses the amplitude and phase distribution required in the plane of the metasurface lens. The phase distribution can be obtained in a discretized manner by means of the phase shifts applied by the elementary resonators. It is thus possible to obtain a focal spot in a ring for example.
    Fig. 4 schematically shows an example of a structured dielectric surface for a metasurface lens according to the second embodiment of the invention, using a circular network of elementary resonators.
    J
    In 410, the structured dielectric layer of thickness - has been shown, the second layer being absent from the zones 420. As indicated above, the structured dielectric layer makes it possible to locally introduce an additional phase shift of 7Î when the phase shift ¢. to apply exceeds π fl in absolute value.
    An advantageous characteristic of the metasurface lenses according to the invention is that they have only a low chromatic aberration. Thus, for a converging lens, the focal distance depends little on the wavelength in the passband of the lens. To do this, the arm lengths are chosen to be different but relatively close to λ
    --- where n is the optical index of the dielectric material within the crosses (i.e.
    2n 3
    Filling the arms of the crosses). More specifically, it is recalled that the thickness of the metal layer gives the quality factor of the resonators and therefore the width of the passband of the lens. The relative difference in arm length is chosen so that the corresponding frequency (or wavelength) difference is less than the width of this pass band. In other words, the difference between the resonance frequency of the long arm and the resonance frequency of the short arm is chosen to be less than the width at half height of the spectral response in transmission of said arms.
    Fig. 5 shows the relative variation of the focal distance as a function of a relative variation of the incident wavelength, for an example of a metasurface lens according to the invention.
    The relative variation in wavelength is shown on the abscissa and the relative variation in focal length on the ordinate.
    Insofar as the focal length is substantially greater than the wavelength (f »λ), it is verified that a variation in wavelength causes only a small variation in the focal distance.
    It is assumed below that the incident wave comprises a first spectral component at the wavelength 2 1 and a second spectral component at the wavelength.
    According to a variant of the first embodiment of the invention, the metasurface lens comprises a first network of sub-wavelength resonators at wavelength 2 1 and a second network of sub-wavelength resonators at The wavelength . In other words, the elementary resonators of the first network are crosses whose arms are of unequal length and close to A and the elementary 2n resonators of the second network are crosses whose arms are of unequal length and close to A.
    2n
    Fig. 6 schematically shows an arrangement of wavelength resonators for a metasurface lens according to this variant.
    611 shows an elementary resonator of the first network and 621624 represents elementary resonators of the second network.
    The cross section of an elementary resonator generally being of the order
    λ while the arm lengths are of the order of -, it is possible to carry out a
    J 2n basic pattern composed of elementary resonators of the first and second networks in which the cross section of each elementary resonator of the first network is covered by the cross section of elementary resonators of the second network.
    Thus, in Fig. 6, the cross section 615 of the elementary resonator 610 is covered by the cross sections 625 of the neighboring elementary resonators 620.
    The elementary resonators of the first and second networks can then be oriented so that the component at wavelength 2 1 converges at a first focal point r i and the component at wavelength converges at a second focal point f 2 , distinct from r i . It will be assumed that the focal points are located at the same focal distance f but off center with respect to the optical axis of the lens. The coordinates of r i and f 2 in the plane Π parallel to the plane of the lens are respectively of coordinates ( % 1 , yj and
    The orientation of an elementary resonator of the first network whose phase center is located at a point p with coordinates ( x , y) in a frame (O, x, y) of the plane of the lens is chosen so as to introduce a phase shift (/ -7 (A “ % ιΓ + (T, · - ΤιΓ + / 2 j with | ^, | <y where is the optical index of the output medium at wavelength 2 1 .
    Similarly, the orientation of an elementary resonator of the second network whose center is located at a point Pj with coordinates (Xj, yj) in the coordinate system (O, x, y) is chosen so as to introduce a phase shift φ Ύ ] . with where n o is the refractive index of the output medium at the wavelength.
    Fig. 7 schematically shows the use of a metasurface lens to perform spectral sorting in polarized light.
    The metasurface lens, designated by 710, is structured to comprise two networks of elementary resonators as described in relation to FIG. 6. The focal points are designated by r i and f 2 . An incident wave arriving on the lens in the direction of the optical axis is focused at point r i for its component at the wavelength 2 1 and at point f 2 for its component at the wave length
    1 2 .
    It is thus possible to sort the two spectral components of the incident wave at points r i and f 2 . Those skilled in the art will understand that this spectral sorting can be generalized without difficulty to more than 2 wavelengths by structuring the metasurface lens in as many networks of resonators as wavelengths to be sorted.
    Fig. 8 schematically represents the use of metasurface lenses for performing four-color imaging.
    More specifically, this figure shows a pixel 800, divided into four elementary sub-pixels, each elementary sub-pixel 801-804 being associated with a metasurface lens whose resonators are centered on a particular wavelength.
    In the present case, the lenses associated with the elementary sub-pixels 801-804 are respectively fixed on the wavelengths 2 pm, 3.3 pm, 3.7 pm and 4.5 pm. The size of the pixel is 30 μm x 30 μm and that of the elementary sub-pixels 15 μm × 15 μm. The index of the output medium (CdTe substrate) is 2.7 and the index of the material filling the arms of the crosses is 2.2 (SiN or ZnS). The focal distance here is 30 µm.
    The metasurface lenses associated with the elementary sub-pixels 801-804 have the structure described in relation to FIGS. 3C and 4.
    It will be understood that each metasurface lens associated with a sub-pixel fulfills both a focusing and filtering function, the intensity of the incident beam being measured at the four wavelengths of interest at four focal points located in the same plan.
    The fact of using for the same lens crosses of the same size but with different orientations makes it possible to obtain filtering with better spectral selectivity than in the prior art (cf. article by X.M. Goh above). In other words, the responses of the different lenses are well separated in wavelength.
    Fig. 9 represents the percentage of photons falling on a portion of the focal plane as a function of the wavelength for the metasurface lens of FIG. 8 associated with the wavelength of 2 pm.
    The portion of the focal plane considered is taken here equal to 9% of the surface of the lens in question. It can be seen that the lens has good spectral selectivity around the central wavelength of the resonators, namely 2 μm. The wavelengths 10 3.3 pm, 3.7 pm and 4.5 pm corresponding to other other elementary sub-pixels are well filtered.
    权利要求:
    Claims (13)
    [1" id="c-fr-0001]
    1. Metasurface lens intended to receive an incident wave of given wavelength, characterized in that it comprises at least a first network of resonators, said resonators of the first network being crosses of identical shape, said first network being located in a plane of the lens, each cross comprising at least a first arm (110), said long arm, extending along a first axis and a second arm (120), said short arm, of length strictly less than the long arm and extending along a second axis, substantially orthogonal to the first axis, each cross phase shifting the incident wave by introducing its own phase shift (φ.) depending on the orientation of the cross (^.) relative to a reference direction in the plane of the lens.
    [2" id="c-fr-0002]
    2. Metasurface lens according to claim 1, characterized in that the length of the long arm is 5% to 10% greater than the length of the short arm.
    [3" id="c-fr-0003]
    3. Metasurface lens according to claim 1 or 2, characterized in that the lengths of the long and short arms are chosen so that the difference between the resonance frequency of the long arm and the resonance frequency of the short arm is less than the width at half height of the spectral response in transmission of each of said arms.
    [4" id="c-fr-0004]
    4. Metasurface lens according to one of the preceding claims, characterized in that the crosses are produced by recesses within a metallic layer, the metallic layer being deposited on a first dielectric layer transparent at said given wavelength .
    [5" id="c-fr-0005]
    5. Metasurface lens according to claim 4, characterized in that the recesses are filled with a material with an optical index higher than the optical index of the first dielectric layer.
    [6" id="c-fr-0006]
    6. Metasurface lens according to claim 4 or 5, characterized in that the first dielectric layer is itself deposited on a transparent semiconductor substrate at said given wavelength, the optical index of the substrate being greater than l index of the first dielectric layer.
    [7" id="c-fr-0007]
    7. Metasurface lens according to one of claims 4 to 6, characterized in that a second dielectric layer is deposited on the metal layer, said second dielectric layer being made of the same material as the first layer
    J dielectric and being of thickness - where λ is said given wavelength and h is 2n the index of the first and second dielectric layers.
    [8" id="c-fr-0008]
    8. metasurface lens according to one of claims 4 to 7, characterized in that the metasurface lens is a converging lens, of focal length f and that the orientation of a cross whose center is located at a point p . of coordinates ( x ., y .) in a coordinate system (o, x, y) in the plane of the lens is chosen so as to generate its own phase shift φ. =
    Ί-πη 0 λ with 1 ^ 1 where λ is said given wavelength and n is the index of the output medium of the lens.
    [9" id="c-fr-0009]
    9. metasurface lens according to claim 7, characterized in that the metasurface lens is a converging lens, of focal length f and that the orientation of a cross whose center is located at a point p of coordinates (x. , y.) in a reference (O, x, y) in the plane of the lens is chosen so as to generate a proper phase shift ¢ ,. = ¢, mod - with ¢. = ---- a- f -dxf + y 2 + f 2 , where n o is the index of the output medium of
    2 λ ') °
    J the lens, a third thick dielectric layer - being deposited only read
    TC above the crosses for which - <p | <π
    [10" id="c-fr-0010]
    10. Metasurface lens according to any one of the preceding claims, characterized in that the orientation of the crosses can only take a finite set of discrete angular values.
    [11" id="c-fr-0011]
    11. Metasurface lens according to any one of the preceding claims, characterized in that the first network is periodic.
    [12" id="c-fr-0012]
    12. Metasurface lens according to one of claims 4 to 8, characterized in that it comprises a second network of resonators, the resonators of the second network being crosses of identical shapes, the second network being located in the plane of the lens, each cross of the second network also being located in an effective cross-section of the size of a cross of the first network, the crosses of the second network being of size smaller than that of the crosses of the first network, each cross of the second network also comprising a long arm and a short arm, each cross of the second grating dephasing the incident wave by its own phase shift depending on its orientation, within the plane of the lens, with respect to said reference direction.
    [13" id="c-fr-0013]
    13. metasurface lens according to claim 12, characterized in that the incident wave comprises a first spectral component at a first wavelength 2 1 and a second spectral component at a second wavelength z 2 , than the lens with metasurface is a converging lens, of focal length f, that the orientation of a cross of the first grating whose center is located at a point p. of coordinates ( x ., y .) in a coordinate system (o, x, y) of the plane of the lens is chosen so as to generate its own phase shift (/ -7 (T “V) 2 + (T -Ti) 2 + / 2 j with | ^, | <y where n o is the optical index of the output medium of the lens, at the wavelength, and that the orientation of a cross of the second grating whose center is located at a point Pj with coordinates (^, in the coordinate system (O, x, y) is chosen so as to generate a
    5 proper phase shift ~ j ( x j ~ χ ι Γ + © “T 2 / + / 2 ^ with KJ <f where is the optical index of the output medium of the lens, at the wavelength q 2 .
    S.61050
    1/7
    210
    2Π
    76-5--4--3-2--1- Û - Èt ± $$ ± $ tttl ± t ±· 3 ^^^ NT '^' Sr 'Φ'Η'Τ' * 1 ^ Îcl- jîîL fc ^ Swi ^ 3 &<^ Λίπ · fc4jL-jà £ j · Λ3 *. * 2 ^ ί ji iato; oîîoWîî ¢ ίoî ± tq
    X & A ^ AAAAæ ^^ A ^ lotoWtoWttiotîd
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    EP3568719A1|2019-11-20|
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JP2010054915A|2008-08-29|2010-03-11|Canon Inc|Optical phase controller and optical phase control method|
    WO2015063762A1|2013-10-28|2015-05-07|Ramot At Tel-Aviv University Ltd.|System and method for controlling light|KR20180090613A|2017-02-03|2018-08-13|삼성전자주식회사|Meta optical device and method of fabricating the same|
    US11222987B2|2018-03-21|2022-01-11|Intel Corporation|Optical receiver employing a metasurface collection lens having concentric belts or rings|
    CN110109202A|2019-04-29|2019-08-09|南京理工大学|Super surface lens|
    CN110850601B|2019-11-29|2020-10-13|武汉大学|Method for realizing image addition and subtraction operation by using super surface|
    CN112684522B|2020-11-26|2021-12-31|中国科学院上海微系统与信息技术研究所|Ultraviolet and visible light common-lens double-light-path imaging detection system and manufacturing method thereof|
    法律状态:
    2018-01-31| PLFP| Fee payment|Year of fee payment: 2 |
    2018-07-20| PLSC| Publication of the preliminary search report|Effective date: 20180720 |
    2020-01-30| PLFP| Fee payment|Year of fee payment: 4 |
    2021-01-28| PLFP| Fee payment|Year of fee payment: 5 |
    2022-01-31| PLFP| Fee payment|Year of fee payment: 6 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1750289|2017-01-13|
    FR1750289A|FR3061962B1|2017-01-13|2017-01-13|FOCUSING METASURFACE LENS AND LOW CHROMATIC ABERRATION|FR1750289A| FR3061962B1|2017-01-13|2017-01-13|FOCUSING METASURFACE LENS AND LOW CHROMATIC ABERRATION|
    US16/477,359| US11119251B2|2017-01-13|2018-01-11|Lens with focusing metasurface and low chromatic aberration|
    PCT/FR2018/050061| WO2018130786A1|2017-01-13|2018-01-11|Lens with focusing metasurface and low chromatic aberration|
    EP18702759.4A| EP3568719A1|2017-01-13|2018-01-11|Lens with focusing metasurface and low chromatic aberration|
    IL267741A| IL267741D0|2017-01-13|2019-06-30|Lens with focusing metasurface and low chromatic aberration|
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