An imaging device is presented for use in an imaging system capable of improving the image quality. The imaging device has one or more optical systems defining an effective aperture of the imaging device. The imaging device comprises a lens system having an algebraic representation matrix of a diagonalized form defining a first Condition Number, and a phase encoder utility adapted to effect a second Condition Number of an algebraic representation matrix of the imaging device, smaller than said first Condition Number of the lens system.

The invention provides a method for designing a diffractive optical element, characterized in comprising: S101: obtaining a first optical field pattern on a target plane; S102: converting the first optical field pattern on the target plane into a second optical field pattern on a spherical surface; S103: compensating for missing points of the second optical field pattern on the spherical surface, and matching grayscale values, so as to obtain a corrected third optical field pattern; and S104: obtaining a phase distribution of the diffractive optical element according to the third optical field pattern. By means of the design method, the projection quality of a diffractive optical element is improved.

An apparatus for sorting orbital angular momentum eigenstates of one or more photons includes at least one transformation PBOE configured to sort orbital angular momentum eigenstates of the one or more photons, at least one phase correction PBOE configured to sort spin angular momentum eigenstates of the one or more photons. A method for sorting orbital angular momentum eigenstates of one or more photons includes using at least one transformation PBOE to sort orbital angular momentum eigenstates of the one or more photons, and using at least one phase correction PBOE to sort spin angular momentum eigenstates of the one or more photons.

A wideband diffractive component capable of diffracting an incident beam exhibiting a wavelength lying in a diffraction spectral band, the diffractive component elementary areas arranged on a surface, each area belonging to a type indexed by an index i lying between 1 and n, with n greater than 1, index i corresponding to blaze wavelength λi of index i, the blaze wavelengths lying in the diffraction spectral band, an elementary area of type i comprising microstructures having at least a size less than 1.5 times the blaze wavelength of index i, the microstructures arranged to form an artificial material exhibiting an effective index variation such that an elementary area of type i constitutes a blazed diffractive element at the blaze wavelength λi of index i, the different values of the blaze wavelengths and the proportion of surface area occupied by the areas of a given type a function of a global diffraction efficiency desired in the diffraction spectral band.

A grating coupler couples a waveguide to a beam and is formed of patterned shapes in a first and second layer of planar material, the shapes embedded in background material, the layers separated by less than one wavelength. The shapes are organized as a plurality of adjacent unit cells arranged along a direction of propagation of light with each unit cell including a shape of the first material and a shape of the second material, each unit cell having design parameters including a period, a width wb of the shape of first planar material, a width wt of the shape of second planar material, and an offset between the shapes. The coupler has a directivity ratio D is at least 10 dB between “up” and “down” radiation; and unit cells differ in at least one parameter selected from period, wb, wt, and offset to provide a predetermined beam shape.

A method of conical anisotropic rigorous coupled wave analysis for grating and a computing device are disclosed. The method comprises: obtaining a target geometric phase δ′.sub.g for the anisotropic-material-based grating; obtaining a slow axis azimuth angle ϕ.sub.c(x) of the anisotropic-material-based grating according to the target geometric phase δ′.sub.g; obtaining a permittivity tensor of the anisotropic-material-based grating, wherein the anisotropic-material-based grating has an ordinary index n.sub.o and an extraordinary index n.sub.e, the anisotropic-material-based grating has a slow axis polar angle θ.sub.c and slow axis azimuth angle ϕ.sub.c(x), and the permittivity tensor is based on n.sub.o, n.sub.e, θ.sub.c and ϕ.sub.c(x); applying the permittivity tensor into Maxwell equations; obtaining electromagnetic field for the anisotropic-material-based grating by using boundary conditions of at least two layers or sublayers of the anisotropic-material-based grating and Maxwell equations for each layer or sublayer, to obtain a diffraction efficiency for the anisotropic-material-based grating.

An imaging device is presented for use in an imaging system capable of improving the image quality. The imaging device has one or more optical systems defining an effective aperture of the imaging device. The imaging device comprises a lens system having an algebraic representation matrix of a diagonalized form defining a first Condition Number, and a phase encoder utility adapted to effect a second Condition Number of an algebraic representation matrix of the imaging device, smaller than said first Condition Number of the lens system.

A periodic optimization method for a diffractive optical element includes converting coordinates of individual target spots of a target spot array into angular spectrum coordinates, selecting an initial period, calculating diffraction orders of individual target spots, rounding the diffraction order, calculating the coordinates of actual projection spots by using the rounded diffraction orders, calculating evaluation indicator of period optimization, adjusting the period, and repeating the steps, and comparing the evaluation indicators to determine an optimal period for the diffractive optical element. With the periodic optimization method, an actual spot array is made to match a target spot array to the greatest possible extent with a small amount of calculations, thereby improving the design quality and accuracy of a diffractive optical element.

A grating coupler couples a waveguide to a beam and is formed of patterned shapes in a first and second layer of planar material, the shapes embedded in background material, the layers separated by less than one wavelength. The shapes are organized as a plurality of adjacent unit cells arranged along a direction of propagation of light with each unit cell including a shape of the first material and a shape of the second material, each unit cell having design parameters including a period, a width wb of the shape of first planar material, a width wt of the shape of second planar material, and an offset between the shapes. The coupler has a directivity ratio D is at least 10 dB between “up” and “down” radiation; and unit cells differ in at least one parameter selected from period, wb, wt, and offset to provide a predetermined beam shape.

A periodic optimization method for a diffractive optical element includes converting coordinates of individual target spots of a target spot array into angular spectrum coordinates, selecting an initial period, calculating diffraction orders of individual target spots, rounding the diffraction order, calculating the coordinates of actual projection spots by using the rounded diffraction orders, calculating evaluation indicator of period optimization, adjusting the period, and repeating the steps, and comparing the evaluation indicators to determine an optimal period for the diffractive optical element. With the periodic optimization method, an actual spot array is made to match a target spot array to the greatest possible extent with a small amount of calculations, thereby improving the design quality and accuracy of a diffractive optical element.