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Abstract Dynamic and responsive structural color devices present promising opportunities for sensing and display technologies, with applications including point‐of‐care diagnostics, portable/wearable sensors, and low‐power full‐color displays. However, it is often difficult to generate a large and quantitatively meaningful colorimetric response especially toward weak stimuli. Here, dual‐band hyperchromatic structural color (HSC) is presented as an approach to overcome these challenges. Within this framework, a dual‐band mesoporous silicon rugate filter metamaterial co‐designed is experimentally realized for use with a dichromatic (red/green) illuminant. This is shown to enable an amplified red‐to‐green color transition with a substantially smaller wavelength shift than conventional structural color devices, Δλ ≪ |λ_G–λ_R|, as well as a direct quantitative mapping between the observed chromaticity and the input stimulus. This approach is experimentally demonstrated for the spatiotemporally resolved sensing of refractometric stimuli including small‐molecules and volatile organic compounds (VOCs) with a ≈0.08 nm equivalent spectral resolution. This approach is entirely scanning‐free, enabled by simple color imaging, and does not require advanced spectroscopic (hyperspectral) imaging or interferometric imaging to obtain meaningful quantitative and spatiotemporally resolved information pertaining to the sensor's attributes. These results demonstrate dual‐band HSC as a promising approach for realizing low‐cost and high performance dynamic structural color devices and sensors. 

We introduce the design, fabrication, and experimental investigation of subwavelength Fano resonant porous silicon metasurfaces functioning on the principle of guided mode resonance. These metasurfaces exhibit promise for dynamic structural coloration and sensing applications. 

Production of flat optics incorporating subwavelength features, particularly at visible frequencies, remains a significant challenge. Here, we establish a framework for the design of effective medium metasurfaces (EMM), relying on nanoimprinting of mesoporous silicon to realize a patterned refractive indexn(x,y) corresponding to an arbitrary transmitted phase profileϕ(x,y). The method is used to design the stamp profile required to produce a Fresnel lens and the theoretical performance of the metalens is examined using the finite-difference time-domain method. Additionally, we demonstrate neural network aided Monte Carlo analysis as a method to model the effects of metasurface fabrications errors on EMM performance and process yield. 

We present an approach to achieve highly responsive structural color utilizing dual-band porous silicon rugate filter metamaterials combined with dichromatic laser illumination. Spatiotemporally resolved sensing experiments are reported. 

We report the fabrication of gradient index flat optics and waveguides using the ‘nanoimprinting refractive index’ (NIRI) technique applied to mesoporous silicon substrates. Optical wavefront shaping and waveguiding are demonstrated in the visible and near-infrared respectively.