Metasurfaces can be programmed for a spatial transformation of the wavefront, thus allowing parallel optical signal processing on-chip within an ultracompact dimension. On-chip metasurfaces have been implemented with two-dimensional periodic structures, however, their inherent scattering loss limits their large-scale implementation. The scattering can be minimized in single layer high-contrast transmitarray (HCTA) metasurface. Here we demonstrate a one-dimensional HCTA based lens defined on a standard silicon-on-insulator substrate, with its high transmission (<1 dB loss) maintained over a 200 nm bandwidth. Three layers of the HCTAs are cascaded for demonstrating meta-system functionalities of Fourier transformation and differentiation. The meta-system design holds potential for realizing on-chip transformation optics, mathematical operations and spectrometers, with applications in areas of imaging, sensing and quantum information processing.

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The exceptionally high optical nonlinearities, wide bandgap, and homogeneity in solution‐processed metal‐halide perovskite media are utilized as optical nonlinear elements on a silicon photonic platform for low‐power‐active components, such as all‐optical switches, modulators, and lasers. With room temperature back‐end‐of‐line compatible processing, a hybrid metal‐halide perovskite (CH3NH3PbI3) microring resonator (MRR) structure is fabricated on a foundry‐processed low‐loss silicon photonic platform. With in‐plane excitation near the light intensity of 110 W m−2, strong two‐photon absorption and free‐carrier absorption saturation are observed. With 103 field enhancements by MRRs, the photorefractive effect in the metal‐halide perovskite reduces linear absorption, represented by 102 improvement of the MRR's intrinsic quality factor and 20 dB enhancement of the extinction ratio.

demonstrated to improve the light emission efficiency through enhancing light outcoupling efficiency [1,2] and spontaneous emission rate. [3][4][5] Nanophotonic engineering can lead to narrowband and directive light emission. [6][7][8] Chalcogenide materials with unique phase change properties have been explored for tunable thermal emission [9] or reflection [10] in infrared wavelength ranges. PhC waveguide has been demonstrated on thin-film chalcogenide by e-beam lithography, showing slow light and resonance-enhanced parametric nonlinear process in material. [11,12] To reduce cost and improve scalability, solution-processed chalcogenide nanostructure is recently reported through solution process and self-assembling. [13] In this work, we demonstrate the first active chalcogenide metasurface fabricated by self-assembling with tunable dimensions. The nanophotonic structure is tailored to enhance the light emission efficiency through resonance-enhanced absorption of excitation, suppressing guided mode at emission wavelength and Purcell enhancement. [14][15][16][17] The 2D hexagonal chalcogenide nanorod arrays are self-assembled [13] on a silicon template through solution processing. [18][19][20][21][22][23][24] Silicon nanophotonic structure with a few nanometer surface roughness enables delamination of top and bottom bulk chalcogenides during solvent evaporation leaving only a filled nanorod array. Nanophotonic confinement can simultaneously manifest local photon density for enhanced Subwavelength periodic confinement can collectively and selectively enhance local light intensity and enable control over the photoinduced phase transformations at the nanometer scale. Standard nanofabrication process can result in geometrical and compositional inhomogeneities in optical phase change materials, especially chalcogenides, as those materials exhibit poor chemical and thermal stability. Here the self-assembled planar chalcogenide nanostructured array is demonstrated with resonance-enhanced light emission to create an all-dielectric optical metasurface, by taking advantage of the fluid properties associated with solution-processed films. A patterned silicon membrane serves as a template for shaping the chalcogenide metasurface structure. Solution-processed arsenic sulfide metasurface structures are self-assembled in the suspended 250 nm silicon membrane templates. The periodic nanostructure dramatically manifests the local lightmatter interaction such as absorption of incident photons, Raman emission, and photoluminescence. Also, the thermal distribution is modified by the boundaries and thus the photothermal crystallization process, leading to the formation of anisotropic nanoemitters within the field enhancement area. This hybrid structure shows wavelength-selective anisotropic photoluminescence, which is a characteristic behavior of the collective response of the resonantguided modes in a periodic nanostructure. The resonance-enhanced Purcell effect can manifest the quantum efficiency of localized light emission.