Fig. 1. Schematic of optical field manipulation based on on-chip integrated artificial microstructures

Fig. 2. Input-coupling manipulation based on on-chip integrated artificial microstructure. (a) Schematic of Si₃N₄ waveguide with an array of gold nano-antennas^[73]; (b) schematic of an integrated antenna-dimer on a micro-disk^[79]; (c) variation of local density of states enhancement factor (dashed line) and directionality (solid line) as a function of frequency shift ω-ωc between two antennas^[79]; (d) schematic of spin-selective and wavelength-selective demultiplexing based on on-chip integrated geometric phase metasurface^[83]; (e) electric field amplitude distribution in x-y plane bisecting waveguide for right-handed circularly polarized incident light with different wavelengths^[83]; (f) schematic of on-chip multi-band PSHE based on metasurface integrated microcavity^[85]; (g) distribution of electric field components on cross-section of waveguide and microcavity for left-handed circularly polarized incident light with different wavelengths^[85]

Fig. 3. In-plane manipulation of waveguide modes based on on-chip integrated etching microstructures. (a) Schematic of a waveguide mode converter based on shallow-etched metasurfaces^[90]; (b) refractive index distribution of metasurface required for mode conversion^[90]; (c) schematic of ultra-compact on-chip low-loss metalens. Eleven single-mode waveguides are placed on output plane to obtain light intensity distribution^[56]

Fig. 4. In-plane manipulation of waveguide modes based on on-chip integrated metasurfaces. (a) Electric field intensity distribution measured by scanning near-field optical microscopy based on end-coupling^[99]; (b) schematic of a Bessel beam generator formed by a two-dimensional array of plasmonic nano-resonators integrated on SOI waveguide^[99]; (c) transverse profiles of input and output beams fitted with Gaussian and Bessel-Gaussian functions, respectively^[99]; (d) schematic of an on-chip integrated nonlinear photonics device structure^[60]; (e) conceptual diagram of SHG process^[60]

Fig. 5. One-dimensional optical field manipulation of far-field radiation from guided wave-driven metasurfaces. (a) Schematic of guided wave-driven metasurface for far-field radiation manipulation^[66]; (b) electric field distribution of extracted light from phase-gradient metasurface driven by forward propagating (above) and backward propagating (below) guided waves^[66]; (c) schematic of on-chip integrated multifunctional metasurface for lithium niobate on insulator (LNOI) photonic circuit^[118]; (d) schematic of silicon waveguide integrated metasurface for switchable beam focusing^[119]

Fig. 6. Multi-dimensional manipulation of far-field radiation using guided wave-driven metasurfaces with single-port input. (a) Schematic of microdisk resonator dressed by a chain of plasmonic antenna^[121]; (b) mode decomposition histogram for radial, V-shaped, and Λ-shaped structures. In each graph, m-N=-1^[121]; (c) schematic of guided wave-driven geometric metasurface for far-field phase and polarization control. Insets are scanning electron microscope images of fabricated samples that can generate different polarization states^[122]; (d) Fourier plane images of x-polarized and y-polarized lights radiated from samples A and B obtained experimentally^[122]; (e) schematic of a leaky-wave metasurface supporting q-BICs^[124]

Fig. 7. Multi-dimensional manipulation of far-field radiation using waveguide-driven metasurfaces with multi-port input. (a) On-chip integrated metasurfaces for semi-transparent screen display in sync with holographic projection^[127]; (b) external extraction efficiency of meta-diatoms as a function of displacement D between two meta-atoms at a wavelength of 633 nm^[127]; (c) schematic of higher-order Poincaré sphere (HOP) beams achieved by metasurfaces integrated on LNOI platform. Inset is illustration of HOP^[125]