School of Physics - Research Publications

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Optical image processing with metasurface dark modes

Roberts, A ; Gomez, DE ; Davis, TJ (OPTICAL SOC AMER, 2018-09-01)

Here we consider image processing using the optical modes of metasurfaces with an angle-dependent excitation. These spatially dispersive modes can be used to directly manipulate the spatial frequency content of an incident field, suggesting their use as ultra-compact alternatives for analog optical information processing. A general framework for describing the filtering process in terms of the optical transfer functions is provided. In the case where the relevant mode cannot be excited with a normally incident plane wave (a dark mode), high-pass filtering is obtained. We provide examples demonstrating filtering of both amplitude and pure phase objects.
Metasurfaces, dark modes, and high NA illumination

Wesemann, L ; Achmari, P ; Singh, K ; Panchenko, E ; James, TD ; Gomez, DE ; Davis, TJ ; Roberts, A (OPTICAL SOC AMER, 2018-10-15)

The interaction of a focused beam with a metasurface supporting dark modes is investigated. We show computationally and experimentally that the excitation of dark modes is accompanied by characteristic changes in the reflected Fourier spectrum. This spatial frequency filtering capability indicates an avenue for the all-optical, on-chip detection of phase gradients for biological and other imaging techniques.